The glossary
All terms, A–Z
355 plain-English explainers. Search for a phrase, filter by topic, or browse alphabetically.
A/B Testing
An A/B test randomly gives comparable groups of users different experiences and measures whether a chosen outcome changes, helping distinguish a real effect from ordinary variation.
Abstraction
An abstraction offers a simpler way to use a capability by hiding details the user does not need.
Activation
Activation is when a new user first gets meaningful value from a product. Teams estimate it using an action linked to continued use.
AI Agent
An AI agent is software that uses a model to choose steps toward a goal, then uses tools to carry them out and check the results.
AI Assistant
An AI assistant is an app that uses AI models to help people ask questions, draft work, analyse information, or complete tasks.
AI Evaluation
AI evaluation tests an AI product on realistic tasks to see how well it works, what goes wrong, and whether changes improve it.
AI Guardrails
AI guardrails are rules and checks that limit what an AI product can see, say, or do, such as restricting private data or requiring approval for an action.
AI Hallucination
An AI hallucination is a convincing answer that contains made-up, false, or unsupported information.
AI Harness
An AI harness is the software around an AI model that supplies context, connects tools, and controls how its work is checked.
AI Prompt
A prompt is the request and supporting information an AI model receives. Prompt engineering means shaping that input to get more useful answers.
AI Temperature
Temperature is an AI setting that affects how much its replies vary. Lower values favour more likely next pieces of text; higher values give less likely choices more of a chance.
AI Tokens
An AI token is a small piece of text a language model processes. Token counts affect how much text it can handle at once and often determine usage limits and cost.
AI Tool Calling
Tool calling lets an AI model ask its app to use another product or service. The app checks the request, makes the call, and passes back the result.
Algorithm
An algorithm is a set of steps for producing a result, such as sorting a list or ranking posts in a feed.
Alpha, Beta & General Availability GA
Alpha is an early test; beta widens testing; general availability (GA) means a release is ready for normal production use. Exact terms vary by provider.
Amazon EC2 EC2
Amazon EC2 lets teams rent virtual servers from AWS to run software without owning the physical machines.
Amazon OpenSearch Service
Amazon OpenSearch Service runs search software on AWS, helping teams search product information or investigate application logs without running the servers themselves.
Amazon S3 S3
Amazon S3 is an AWS service for storing files and other data in named containers called buckets.
Amazon Web Services AWS
Amazon Web Services (AWS) is Amazon’s cloud provider platform.
Analytics
Analytics turns recorded activity into numbers and patterns that help a team see how people use a product.
Angular
Angular is a framework for building browser applications, with built-in patterns for organising screens and services.
API Endpoint
An API endpoint is a specific place where an app sends a request for information or an action.
API Gateway
An API gateway gives an app one place to send requests, directs them to the right service, and applies shared rules such as access checks and request limits.
API Key, Access Token & Secret
An API key identifies an app or project and may give it access. An access token gives a user or app permission to do specific things, usually for a limited time. A secret is any private value that must be protected.
App Store Review
App store review is when a store checks an app or update against its rules before people can download it.
App Version & Minimum Supported Version
An app version identifies the release on a device. The minimum supported version is the oldest one that can still use the app’s online service.
Application Programming Interface API
An API is an agreed way for one piece of software to ask another for information or an action.
Arrays
An array keeps items in an order so a program can work through them or pick one by its position.
Artificial Intelligence AI
Artificial intelligence is software that performs tasks associated with human abilities. An AI model is the trained component that takes input and produces an output.
Audit Log
An audit log records who did what in a product or service, when it happened, and whether it worked.
Authentication vs Authorisation AuthNAuthZ
Authentication checks who you are. Authorisation decides what you can see or do.
AWS Elastic Beanstalk
Elastic Beanstalk is an AWS service that sets up servers and related resources to help teams launch and run an app.
Backlogs, Sprints & Agile
A backlog orders potential work. A sprint is a fixed period some teams use to tackle selected work. Agile is a broader approach built around small steps, feedback, and adaptation.
Backup & Disaster Recovery DR
A backup is a spare copy of data. Disaster recovery is a tested plan to get a service running again after a major failure.
Backward Compatibility
A backward-compatible change lets existing clients and integrations keep working with a new version without modification.
Batch vs Streaming Data
Batch processing works on collected data at set times; streaming processes new data as it arrives.
Benchmarking
Benchmarking uses repeatable tests to measure how quickly a system completes a task or how much work it can do, then compares the results.
BigQuery
BigQuery is a Google Cloud service for storing and analysing large amounts of data, often to produce reports.
Bitbucket
Bitbucket is Atlassian’s Git hosting provider for sharing code and collaborating on software projects.
Branching
A branch is a separate path of saved changes to a project. It lets people work in parallel before combining their work with the main version.
Breaking Change
A breaking change alters how a product works so existing users or software may need to adapt to keep using it.
Browser Storage
Browser storage lets a website save information in your browser for later pages or visits.
Bugs & Debugging
A bug is software behaving differently from how it should. Debugging means repeating the problem, finding its cause, and checking that a fix works.
Build & Artifact
A build turns source files into a usable version of software. A build artifact is a file or package the process produces.
Business Intelligence BI
Business intelligence turns prepared data into reports and dashboards that help people track performance and make decisions.
Business-to-Business vs Business-to-Consumer B2BB2C
B2B products are sold to organisations; B2C products are sold to individuals. That affects who chooses and uses the product, how they get started, and how success is measured.
C
C is a programming language often used where software needs close control over a computer’s memory and hardware.
C#
C# is a programming language used for services, desktop software, and games, commonly with the .NET platform.
C++
C++ is a programming language used when software needs detailed control over performance and computer resources.
Cache
A cache keeps a temporary copy so software can reuse it quickly without fetching or producing it again.
Canary & Blue-Green Deployment
A canary deployment gives a new version to a small group of users first. A blue-green deployment prepares a separate setup, then switches users to it.
Cascading Style Sheets CSS
CSS sets how a webpage looks and lays out its content, including colours, fonts, spacing, and how it fits different screens.
ChatGPT
ChatGPT is OpenAI’s AI assistant app.
Circuit Breaker
A circuit breaker temporarily stops an app from calling a failing service, then tests whether it works again.
Claude
Claude is Anthropic’s AI assistant and the name of its model family.
Client & Server
A client asks for information or an action; a server handles the request and sends back a response.
Clone vs Fork
Cloning copies a repository to your computer. Forking creates a separate copy on a hosting service, usually in your own account.
Cloud Computing
Cloud computing means using servers, file storage, and other services over a network instead of running all the physical hardware yourself.
Cloud Provider
A cloud provider runs data centres and offers computing, storage, and other services that organisations can use without owning the physical hardware.
Cloud Region & Availability Zone AZ
A cloud region is a geographic area where a provider runs services. An availability zone is a separate location within that region.
Cloudflare
Cloudflare provides services that help websites direct traffic, load content faster, and block unwanted requests.
Code Coverage
Code coverage shows which parts of a program ran during automated tests. It helps find untested code, but a high percentage does not show whether the tests check the right things.
Code Review
Code review is when another developer checks a proposed change and discusses whether it is correct, clear, safe, and ready to merge.
Command-Line Interface CLI
A command-line interface lets you control software by typing commands, making repeated tasks easier to automate.
Compiler vs Runtime
A compiler translates code into a form a computer can run, usually before the program starts. A runtime provides what the program needs while it runs.
Concurrency vs Parallelism
Concurrency means handling several tasks over the same period; parallelism means doing several tasks at the same time.
Configuration
Configuration means the settings that tell software how to behave in a particular environment without changing its code.
Confluence
Confluence is a shared workspace for writing, organising, and finding team documents and knowledge.
Consent Management
Consent management records and follows people’s choices when their permission is needed to use data.
Containers & Docker
Containers run apps from packages of their code and supporting files, helping them work more consistently across computers. Docker is a common set of tools for making and running containers.
Content Delivery Network CDN
A CDN keeps copies of website content on servers in many places, letting visitors load it from somewhere nearby.
Content Management System CMS
A CMS lets people create, organise, review, and publish content without editing source code for every change.
Context Engineering
Context engineering is choosing and organising the information an AI model receives for a request, such as instructions, past messages, documents, and available tools.
Continuous Integration & Delivery CI/CD
CI/CD automates checks when code changes are combined and prepares, or sometimes performs, deployment. It makes frequent, smaller releases easier to manage.
Conversion Rate CVR
Conversion rate is the percentage of people who complete a chosen action, such as signing up or buying, out of those who had the chance to do so.
Cookies & Sessions
A cookie is a small piece of information saved in your browser. A session lets a website recognise you as you move between pages, often using a cookie.
Coupling & Cohesion
Coupling is how much one part of a system depends on another. Cohesion is how closely the jobs within one part fit together.
Create, Read, Update, Delete CRUD
CRUD stands for create, read, update, and delete: four basic ways software handles stored information.
Credential
A credential is something a person or app uses to prove identity or gain access, such as a password, passkey, or API key.
Cron Job
A cron job is a task a computer runs on a schedule, such as sending a daily report or clearing old records.
Cross-Origin Resource Sharing CORS
CORS lets a server tell browsers which other websites may read its responses.
Cross-Site Request Forgery CSRF
CSRF tricks a signed-in person’s browser into sending a request they did not intend, using their existing sign-in.
Cross-Site Scripting XSS
Cross-site scripting (XSS) lets an attacker’s content run as code in a visitor’s browser when a website displays it unsafely.
Customer Acquisition Cost & Lifetime Value CACLTV
CAC estimates the average cost of winning a customer; LTV estimates the revenue or profit that customer brings over time.
Customer Relationship Management CRM
A CRM helps teams track customers and potential customers, their conversations, and related sales or support work.
Daily Active Users, Weekly Active Users & Monthly Active Users DAUWAUMAU
DAU, WAU, and MAU count distinct users active in a day, week, or month. The result depends on what the team counts as “active.”
Data
Data is information recorded in a form that people or computers can store, use, or share.
Data Anonymisation
Anonymisation aims to make identifying people impractical. Pseudonymisation can swap names for codes while keeping a way to reconnect them.
Data Breach
A data breach occurs when protected information is exposed, changed, lost, or made unavailable.
Data Governance
Data governance is how an organisation agrees what its data means, who is responsible for it, who can use it, and how it is protected.
Data Lake vs Data Warehouse
A data lake keeps varied data much as it arrived. A data warehouse organises selected data for analysis and consistent reports.
Data Lineage
Data lineage records where information came from, how it changed, and where it is used.
Data Migration
A data migration moves or changes existing information so it works in a new system or format without losing its meaning.
Data Normalisation
Data normalisation organises a database so shared details are stored once and linked where needed, reducing conflicting copies.
Data Pipeline
A data pipeline is a series of automated steps that collects information, checks or changes it, and sends it where it is needed.
Data Quality
Data quality describes whether information is accurate, complete, timely, and consistent enough for the job people need it to do.
Data Retention
Data retention is a plan for how long to keep information, why, and when to delete or anonymise it.
Data Structures
A data structure is a way to organise information in a program so it can be stored, found, and changed.
Database DB
A database is an organised store of information that software can find and update, such as customer accounts or orders.
Database Index
A database index is a lookup list that helps find records without checking them all.
Database Query
A database query is a question or instruction sent to a database to find, summarise, or change stored information.
Database Transaction
A database transaction makes several related changes together: either all are saved or none are.
Datadog
Datadog helps teams see how apps and servers are running and can alert them to errors, slowdowns, and other problems.
Deep Link
A deep link opens a specific page or action in an app instead of its home screen.
Definition of Done DoD
A definition of done is a team’s shared standard for when work is complete, covering checks such as review, testing, accessibility, and documentation.
Dependency & Package
A package is a reusable bundle of code. When a project needs it to build or run, that package is a dependency.
Deployment vs Release
Deployment puts a new software version in place. Release lets users access its changes. The two can happen at different times.
Deprecation & End of Life EOL
Deprecation warns that a feature or version is being phased out. End of life (EOL) is when its support ends or it is retired.
Design System
A design system gives teams reusable interface parts and guidance so a product looks and works consistently.
Development Environments
Development environments are separate places where a team builds, tests, and runs software. Local work usually happens on a developer’s computer; shared test, staging, and production systems usually run on servers.
Device Permissions
Device permissions let you choose whether an app can access your device’s camera, microphone, location, photos or contacts.
DevOps
DevOps is a way for the people who build software and the people who run it to work together on releases and reliability.
Digital Accessibility A11y
Digital accessibility means making websites, apps, and other digital products usable by people with disabilities.
Distributed Denial of Service DDoS
A DDoS attack floods a website or service with requests from many devices, slowing it down or preventing real people from using it.
Distributed System
A distributed system is a group of computers that work together over a network to provide a service.
Document Object Model DOM
The DOM is the browser’s live outline of a webpage. The browser uses it to display and update what you see on screen.
Elasticity
Elasticity is the ability to add computing power when demand rises and reduce it when demand falls.
Elasticsearch
Elasticsearch organises large amounts of information so people can search and analyse it quickly.
Embeddings
An embedding is a list of numbers that represents an item, such as text or an image, so software can find similar items.
Encryption vs Hashing
Encryption hides data so someone with the right key can read it again. Hashing makes a one-way value used to check or compare data.
Engagement
Engagement describes how often and how meaningfully people use a product. Useful measures depend on what the product helps them do.
Environment Variables
Environment variables are named settings given to an app when it runs. They let the same code use different settings in development, testing, and production.
Epic, Story & Task
An epic groups work toward a larger outcome; a story describes value for a user; a task names a specific action.
Event Taxonomy
An event taxonomy is a shared list of names and rules for actions a product records, so reports count the same things consistently.
Event-Driven Architecture EDA
In event-driven architecture, one part of a system announces that something happened so other parts can respond independently.
Eventual Consistency
Eventual consistency means copies of data may disagree for a time after an update, but will agree once updates finish spreading and no new changes occur.
Experience vs User Interface UXUI
UX is the overall experience of using a product; UI is the set of screens and controls people interact with.
Extract, Transform, Load ETL
ETL (extract, transform, load) copies data, prepares it, and puts it in another system, often for reporting.
Feature Flag
A feature flag lets a team deploy code, then turn a feature on or off for selected users.
Figma
Figma lets teams create and review screen designs, reusable components, and clickable prototypes for digital products.
Fine-Tuning
Fine-tuning trains an existing AI model further on chosen examples to help it handle a specific task or writing style.
Firewall
A firewall checks data moving into or out of a network and uses rules to allow or block connections.
Flaky Test
A flaky test passes on some runs and fails on others without a relevant code change. This makes its results hard to trust.
Formatting & Linting
A formatter makes code look consistent; a linter checks code for suspicious patterns and agreed rules.
Framework vs Library
A library provides code you choose to use for a task. A framework sets the project’s structure and decides when to run the code you add.
Freemium
Freemium offers a useful free version with no set end date, while charging for extra features, capacity, or support.
Frontend Frameworks
Frontend frameworks and libraries give developers reusable ways to build the screens and interactions people use in a browser.
Frontend vs Backend
The frontend is the part of a product people see and use; the backend handles data and rules behind the scenes.
Full-Stack Developer
A full-stack developer works on both the parts of a product people use and the systems behind them.
Functional Programming
Functional programming is a way to organise code around functions that turn inputs into outputs while limiting hidden changes.
Generative AI GenAI
Generative AI creates content such as text, images, audio, or code by using patterns learned from examples.
Git Hosting Provider
A Git hosting provider keeps a shared copy of a Git repository online and gives teams tools to review changes and work together.
Git Push vs Pull
Push sends local commits to a remote repository. Pull downloads remote changes and combines them with your local branch.
GitHub
GitHub is a Git hosting provider for sharing code and collaborating on software projects.
GitHub Copilot
GitHub Copilot is an AI tool that helps people working with code by suggesting edits, answering code questions, and assisting with development tasks.
GitLab
GitLab is a Git hosting provider for sharing code and collaborating on software projects.
Go
Go is a programming language often used to build server software, command-line tools, and cloud services.
Google Cloud GCP
Google Cloud (also called GCP) is Google’s cloud provider platform.
Google Gemini
Gemini is Google’s name for an AI assistant and a family of AI models.
Google Workspace
Google Workspace is a set of online tools for writing documents, storing files, working on spreadsheets, and collaborating with a team.
GraphQL
GraphQL lets an app describe the information it needs from an API, so the response contains those details together.
Happy Path
The happy path is the straightforward route through a task when everything works as expected.
Hardcoding
Hardcoding means putting a particular value directly into code instead of letting it come from a setting, user input, or another source.
Health Check
A health check is a quick test a system uses to see whether an app is working and ready to handle requests.
Hosting
Hosting keeps a website or app available on computers that people can reach over a network.
Hotfix
A hotfix is an urgent change to fix a serious problem in a live product, released quickly with essential checks.
HTTP Headers
HTTP headers are labelled details sent with web requests and replies, such as content types, sign-in information, and caching instructions.
HTTP Methods
HTTP methods label web requests to indicate whether an app wants to read, submit, change, or remove something.
HTTP Status Codes
An HTTP status code is a three-digit number that tells a browser or app how its request went.
HubSpot
HubSpot helps teams manage customer and potential customer information alongside marketing, sales, and support work.
Human in the Loop HITL
Human in the loop means a person checks, corrects, or approves an AI system’s output or action at a defined point.
Hyperlink
A hyperlink is a clickable connection that takes you to another page, file, or place in the same page.
HyperText Markup Language HTML
HTML gives a webpage its content and tells the browser what each part is, such as a heading, link, or button.
Hypertext Transfer Protocol & Hypertext Transfer Protocol Secure HTTPHTTPS
HTTP sets the rules for requests and replies on the web. HTTPS adds encryption and checks that the server matches the address you opened.
Idempotency
An idempotent action has the same effect whether it happens once or several times, making retries safer.
Incidents, Rollbacks & Iteration
An incident is an unplanned disruption to a live service. Teams work to limit its impact, restore service, and use what they learn to improve the product and process.
Infrastructure as Code IaC
Infrastructure as code means using files to set up and change servers, databases, and other resources instead of setting them up by hand.
Integrated Development Environment IDE
An IDE is an app that combines a code editor with tools for running, testing, and fixing software.
Integration
An integration connects separate software systems so they can share information or carry out a task together.
IP Address IP
An IP address tells a network where to send data.
Java
Java is a programming language used for many business services, Android apps, and other software.
JavaScript JS
JavaScript is a programming language that helps webpages respond to your actions and update what you see.
JavaScript Object Notation JSON
JSON is a common text format that labels information so different apps can read and exchange it.
Jira
Jira is a tool for recording tasks, bugs, and requests, assigning owners, and tracking progress.
JSON Web Token JWT
A JWT carries details a system can verify. A signature can detect changes but does not encrypt them.
Key Performance Indicator vs Objectives and Key Results KPIOKR
A KPI tracks ongoing performance. An OKR sets a goal for a period and names measurable results that show progress.
Kotlin
Kotlin is a programming language commonly used for Android apps and also for services and other software.
Kubernetes K8s
Kubernetes manages containers across a group of servers, keeping apps running when teams update them or a server fails.
Large Language Model LLM
An LLM is an AI model trained on large amounts of text to produce language, such as answers, summaries, and drafts.
Latency vs Bandwidth
Latency is how long data takes to arrive; bandwidth is how much data a connection can carry each second. A high-bandwidth connection can still feel slow if latency is high.
Legacy System
A legacy system is software an organisation still relies on but finds hard to change or maintain.
Linux
Linux is an operating system family used on servers, computers, and many other devices.
Load Time vs Runtime Performance
Load time is how long a page or app takes to become usable. Runtime performance is how smoothly it responds once you start using it.
Load, Stress & Performance Testing
Performance testing checks how a system responds to demand. Load testing uses expected demand; stress testing pushes beyond it to find where the system slows down or fails.
Low-Code vs No-Code
No-code tools let people build apps and workflows with visual parts; low-code tools work similarly but also allow custom code.
Machine Learning ML
Machine learning finds patterns in examples and uses them to make predictions or create new content.
macOS
macOS is the operating system Apple makes for Mac computers.
Maps & Sets
A map finds a value by a key; a set keeps a collection of unique items.
Markup & Markdown
Markup adds labels to text so software knows its structure; Markdown is a simple way to write formatted text using plain characters.
Memory Leak
A memory leak happens when a program keeps data it no longer needs. Over time, this can make it slow down or stop working.
Memory Usage
Memory usage is how much temporary working space (RAM) a program uses while running. Using too much can slow it down or cause it to stop.
Merge
A merge combines changes from one branch into another, often after the team reviews them.
Merge Conflict
A merge conflict happens when Git cannot safely combine changes and a person must decide what the result should contain.
Message Queue
A message queue holds messages until another part of a system is ready to handle them, so the sender can move on before the work is done.
Metadata
Metadata is information that describes other data, such as a photo’s date, a document’s author, or the fields in a dataset.
Microsoft Azure
Microsoft Azure is Microsoft’s cloud provider platform.
Microsoft Copilot
Microsoft Copilot is an AI assistant that can appear in Microsoft workplace apps when an organisation enables it.
Microsoft Teams
Microsoft Teams is a workplace app for chat, video meetings, shared files, and conversations organised by team or channel.
Middleware
Middleware sits between parts of a system and performs common tasks, such as checking access, recording activity, or translating data.
Minimum Viable Product MVP
An MVP is the simplest usable version of a product that lets a team test an important assumption with real users.
Miro
Miro is a shared online whiteboard for workshops, diagrams, planning, and brainstorming.
Mobile SDK
A mobile SDK (software development kit) is ready-made code and tools for building an app or adding services such as maps and payments.
Mocks, Stubs & Test Doubles
A test double stands in for a real part of a system during testing. A stub gives prepared answers; a mock checks how the software used it.
Model Context Protocol MCP
Model Context Protocol (MCP) is a standard way for AI apps to connect to other software and use its tools, information, and saved instructions.
Model Drift
Model drift is when an AI model becomes less reliable because the real world has changed since it was trained or tested.
Model Training vs Inference
Training uses examples to change a model; inference uses the trained model to answer a new request or make a prediction.
Monitoring, Logging & Alerts
Logs record events, monitoring tracks the health and behaviour of a system, and alerts notify people when important signals suggest that attention is needed.
Monolith vs Microservices
A monolith puts a product’s features in one program; microservices split them into services that can be updated and run separately.
Multi-Factor Authentication MFA
MFA asks for two kinds of proof when you sign in, so a stolen password alone is not enough.
Multi-Tenant Software
Multi-tenant software lets several customer organisations share an application while keeping each one’s users, settings, and data separate.
Multimodal AI
Multimodal AI works with more than one type of content, such as text, images, audio, or video.
Native, Cross-Platform & Hybrid Apps
Native development builds iPhone and Android versions mainly with each system’s own tools. Cross-platform development shares code between them. A hybrid app uses website code inside an installed app and can share it across systems.
Netlify
Netlify is a website deployment platform that builds and hosts websites and can provide preview versions for review.
Network Port
An IP address tells data which device to reach; a port number tells that device which app should receive it.
Node.js & Deno
Node.js and Deno are tools for running JavaScript outside a web browser, often on a server or a developer’s computer.
North Star Metric NSM
A north-star metric is one main measure of the value customers get from a product over time. It gives teams a shared goal.
Notion
Notion is an online workspace where teams combine documents, wikis, simple databases, and project plans.
OAuth & Single Sign-On SSO
Single sign-on (SSO) lets you use one sign-in across several apps. OAuth lets one app get limited access to another service without your password.
Object Storage
Object storage keeps files and other data as named items, often grouped in buckets. It is commonly used for photos, documents, and backups.
Objective-C
Objective-C is a language based on C that is found in older Apple app code and some current Apple software.
Objects
An object groups related information in software and may include actions that use or change it.
Observability
Observability helps teams understand what software is doing by looking at the data it produces, such as errors and response times.
Offline-First
An offline-first app lets you do key tasks without internet. It saves changes on your device and sends them when the connection returns.
On-Call, Runbooks & Escalation
On call means someone is assigned to respond to urgent problems. A runbook gives response steps, and escalation brings in more help.
Open Source & Software Licences
Open-source software makes its source code available under a licence that lets people use, change, and share it, subject to conditions.
Open Worldwide Application Security Project OWASP
OWASP is a nonprofit community that makes free guides and tools for software security, including the web app Top 10.
Open-Weight vs Open-Source AI Models
Open-weight AI shares a model’s learned numbers. Open-source AI also provides the code, information about its training data, and rights needed to use, study, change, and share it.
OpenAI
OpenAI is an AI company that makes models and products, including ChatGPT, and offers an API for developers building AI features into their own software.
OpenSearch
OpenSearch is open-source software for searching and analysing large amounts of information, such as product lists and application logs.
Operating Systems
An operating system is the main software that manages a computer’s hardware and lets other programs run.
Pagination
Pagination splits a long list into smaller groups, so a product can load and show a few results at a time.
Payload
A payload is the main data sent in a request, response, or message, such as order details or an order number.
Penetration Testing
A penetration test is an authorised attempt to find security weaknesses and show how they could be used.
Personally Identifiable Information PII
PII is information that can identify someone, on its own or when combined with other details.
Phishing
Phishing uses a fake message or website to trick someone into sharing information, sending money, or giving access to an account.
PHP
PHP is a programming language often used on web servers to build pages and handle requests.
Platform Engineering
Platform engineering gives software teams shared tools and clear routes for building, releasing, and running services, so they can do routine work themselves.
Polling vs Streaming
Polling checks for updates again and again. Streaming keeps a connection open so updates can arrive as they happen.
Postman
Postman is a tool for sending API requests, inspecting responses, and sharing sets of requests with a team.
Primary Key & Foreign Key
A primary key is a unique ID for one record; a foreign key stores that ID in another record to link them.
Principle of Least Privilege PoLP
Least privilege means giving people and software only the access they need to do their work, for as long as they need it.
Privacy Laws Around the World
Many places have rules for handling personal information, but their scope, rights, and duties are different.
Product Discovery
Product discovery is the work of understanding a user problem and testing whether a proposed solution is useful, usable, and worth building.
Product Manager vs Product Owner
A product manager usually shapes a product’s direction and outcomes. A product owner is accountable for maximising value and managing the product backlog in Scrum. One person may do both jobs.
Product Roadmap
A product roadmap shows where a product is heading, which goals matter most, and roughly when the team plans to work on them. Plans can change as the team learns.
Product-Market Fit PMF
Product-market fit means a product meets a real need for a specific group of customers, shown by lasting use and demand.
Profiling
Profiling shows which parts of a running program use time or memory, helping teams find what causes slowdowns or high memory use.
Programming
Programming means writing instructions that a computer can follow to carry out tasks.
Programming Languages
A programming language is a set of rules for writing instructions that software tools can turn into a running program.
Progressive Web App PWA
A progressive web app is a website that can offer app-like features, such as an icon on your device, some offline access, and notifications.
Prompt Injection vs Jailbreaking
Prompt injection tries to redirect an AI with instructions it should not follow, often hidden in material it reads. A jailbreak tries to bypass its safety rules.
Proof of Concept POC
A proof of concept is a small experiment that tests whether a technical idea can work.
Proxy vs Reverse Proxy
A forward proxy sends requests on behalf of users or devices; a reverse proxy receives requests on behalf of online services.
Pull Request PR
A pull request is a proposal to merge one set of code changes into another. It gives the team a place to review, discuss, and approve the work first.
Push Notification
A push notification is a message from an app that can appear on your phone or tablet even when the app is not open.
Python
Python is a programming language used for tasks such as automation, web services, data analysis, and AI work.
Quality Assurance vs Quality Control QAQC
Quality assurance (QA) improves how a team works to prevent problems. Quality control (QC) checks what the team made to find problems. Software teams often use “QA” for both.
Race Condition
A race condition is a bug where overlapping actions can produce the wrong result depending on their timing or order.
Rate Limiting
Rate limiting sets a maximum number of requests an app or account can make in a set time, helping prevent overload.
React
React is a JavaScript library for building interfaces from reusable pieces called components.
Redirect
A redirect automatically sends your browser from one web address to another, often because a page has moved.
Redundancy & Failover
Redundancy means having another server or service that can do the same job. Failover switches work to it if one fails.
Refactoring & Technical Debt
Refactoring improves code’s structure without changing its behaviour. Technical debt is the future cost of choices that make software harder to change or run.
Regression Testing
Regression testing checks that a change has not broken something that worked before, including features unrelated to the change.
Replication vs Sharding
Replication copies the same data onto several servers; sharding splits a large set of data between servers.
Repository & Commit
A repository holds a project’s files and change history. A commit is a saved checkpoint of a related set of changes.
Request & Response
A request asks another system for information or an action. A response is the reply, which can contain the result or an error.
Requirements & Acceptance Criteria AC
Requirements describe what a solution must achieve, while acceptance criteria provide specific, testable conditions for deciding whether a piece of work meets that need.
Responsive Design
Responsive design makes a website adjust to different screens so it stays easy to read and use on phones, tablets, and computers.
Responsive vs Adaptive App
A responsive app rearranges content to fit the space on a phone or tablet. An adaptive app changes its layout or controls to suit the device or how someone uses it.
REST API REST
A REST API organises web requests around things such as orders, using addresses and standard actions to read or change them.
Retention & Churn
Retention measures how many users or customers keep using or paying for a product over time; churn measures how many stop.
Retrieval-Augmented Generation RAG
RAG looks up relevant information in documents or databases and gives it to an AI model to use in its response.
Role-Based Access Control RBAC
Role-based access control (RBAC) groups permissions by job role, so people get access through the roles they hold.
Rollback vs Rollforward
A rollback restores an earlier software version after a problem. A rollforward applies a new change to fix it.
Root Cause Analysis RCA
Root cause analysis investigates why a problem happened and how to reduce the chance or impact of it happening again.
Rust
Rust is a programming language designed to help developers build fast software while avoiding many memory-related errors.
SaaS vs PaaS vs IaaS SaaSPaaSIaaS
SaaS is ready-to-use software; PaaS runs apps your team builds; IaaS rents servers and other computing resources.
Salesforce
Salesforce is an online platform organisations use to manage customer records, sales, and support.
Sandbox
A sandbox is a separate place to test software or a set of limits on what software can access.
Scaling & Load Balancing
Scaling changes a service’s capacity as demand changes. A load balancer shares incoming requests among servers so no one server has to handle them all.
Schema
A schema sets out what details a record or message should have, how they fit together, and which values are allowed.
Scope Creep
Scope creep is the gradual expansion of work beyond the agreed plan, without a clear decision about the extra time, cost, or priorities.
Scrum vs Kanban
Scrum organises work in short sprints with a goal. Kanban visualises the workflow and limits work in progress to improve flow.
Search Engine Optimisation SEO
SEO is the work of helping search engines understand a website and helping people find useful pages through unpaid search results.
Secrets Management
Secrets management means storing passwords, API keys, and other private codes safely, controlling who can use them, and replacing them when needed.
Secure Shell SSH
SSH (Secure Shell) lets you securely use another computer over a network, often to manage a server.
Security Audit
A security audit checks whether an organisation meets specific security requirements and can show that its safeguards work.
Semantic Search
Semantic search looks for results with a similar meaning to your query, even when they use different words.
Semantic Versioning SemVer
Semantic versioning uses major.minor.patch numbers to signal bug fixes, new features, and breaking changes.
Serverless Computing
Serverless computing lets teams run software without managing individual servers; the cloud provider handles the server capacity.
Service Workers & Web Workers
A web worker runs browser code away from the main page; a service worker can handle requests and saved files for a website.
Service, Component & Module
A module groups related code, a component has a defined job, and a service provides a capability to other parts of a system, often over a network.
SharePoint
SharePoint is a Microsoft tool for organising team sites, documents, pages, and other shared information.
Single Point of Failure SPOF
A single point of failure is one part whose failure can stop a service because there is nothing to take over.
Single Source of Truth SSOT
A source of truth is the agreed place to check a fact when different copies disagree.
Slack
Slack is a workplace messaging service where people talk in channels and direct messages, share files, and connect other tools.
Smoke Testing
A smoke test quickly checks whether a new version’s essential features work, so teams can spot major problems before detailed testing.
Snowflake
Snowflake is a cloud service for bringing data together and analysing it, often to make reports.
Software Development Kit SDK
An SDK is a bundle of code, tools, and instructions that helps developers build for a platform or connect to a service.
Software Development Life Cycle SDLC
The software development life cycle is the name for the repeatable journey from identifying a problem to designing, building, releasing, and improving a software solution.
Software Testing
Software testing checks whether a system behaves as expected and helps the team understand the risk of changing it. Different test types catch different kinds of problems.
Source Code
Source code is the human-readable set of instructions developers write to make software work. Tools turn or interpret those instructions so a computer can run them.
Spike
A spike is a time-limited investigation of a specific question before a team commits to a solution or estimate.
SQL Injection SQLi
SQL injection happens when an app treats someone’s input as part of a database instruction, letting them change what the database does.
SQL vs NoSQL SQLNoSQL
SQL databases commonly use linked tables; NoSQL is a broad label for databases that organise information in other ways, such as documents.
Stacks & Queues
A stack handles the newest item first; a queue handles the oldest item first.
Stakeholder
A stakeholder is a person or group with an interest in a product or project because it can affect them or they can influence its outcome.
Stand-up, Review & Retrospective
A stand-up coordinates daily work, a review gathers feedback on what the team built, and a retrospective improves how the team works.
Stateful vs Stateless
A stateful service remembers information from earlier requests; a stateless service handles each request without relying on its own memory of them.
Story Points & Estimation
Story points compare the size of work for one team, considering effort, complexity, and uncertainty. They are not hours or days.
Stripe
Stripe is a payments platform that businesses use to accept and manage online payments through hosted pages, software integrations, and dashboards.
Structured AI Output
Structured output makes an AI reply follow a set format, such as labelled fields, so other software can read it more easily.
Swift
Swift is a programming language commonly used to build apps for iPhone, iPad, Mac, and other Apple devices.
Synchronous vs Asynchronous
Synchronous work waits for a result before continuing; asynchronous work allows other activity to continue and handles the result later.
Tech Stack
A tech stack is the combination of software tools and services used to build and run a product.
Technical Design & Architecture
Technical design describes how a particular solution will work, while software architecture describes the larger structure, boundaries, and long-lasting choices of a system.
Telemetry
Telemetry is data software sends about how it is working and how people use it, such as errors, speed, and page views.
Terraform
Terraform is a tool that uses files to create and change cloud resources, such as servers and storage.
Threat Modelling
Threat modelling helps a team think through how a product might be attacked or misused, then choose ways to reduce the risk.
Throttling
Throttling slows down work when a system gets too busy, helping it stay usable.
Time to Live TTL
A time to live (TTL) usually says how long a saved copy can be used. For an IP packet, it limits how many network steps the packet can take.
Timeout & Retry
A timeout ends a wait for a reply. A retry repeats a request after a possible temporary failure.
TLS Certificate TLS
A TLS certificate helps your browser check that a website matches the address you opened before using an encrypted HTTPS connection.
Tools Used by Tech Teams
Tech teams use different tools to plan work, share knowledge, design products, write code, test changes, and run services.
Transmission Control Protocol/Internet Protocol TCP/IP
IP directs small pieces of data across networks. TCP tracks the data, resends missing pieces, and puts what arrives in order.
Trees & Graphs
A tree organises items in branches; a graph represents items and the connections between them.
TypeScript
TypeScript adds checks to JavaScript so some mistakes can be caught before code runs.
Unix
Unix is an operating system family whose design shaped many later systems, including macOS and Linux-like systems.
Uptime, Service Level Agreement & Service Level Objective SLASLO
Uptime measures when a service is available. An SLO is a reliability target; an SLA is a formal promise to customers.
URLs, Domains & DNS URLDNS
A URL is a full web address, a domain is the readable name within it, and DNS finds the numerical address for that name.
Usability Testing
Usability testing means watching people try realistic tasks in a product or prototype to see what works and where they struggle.
User Flow
A user flow maps the steps and decisions a person takes to complete a task in a product.
User Persona
A user persona is a short profile of a type of user, based on research into their goals, situation, and challenges.
User Stories & Tickets
A ticket is a trackable unit of work. A user story is one way to describe that work from the perspective of the person who needs the outcome.
Variables & Functions
A variable stores a value under a name. A function is a named set of instructions that can take inputs and return a result.
Vector Database
A vector database stores number lists that represent items and quickly finds the ones most similar to a search.
Velocity
Velocity is the amount of estimated work a team finishes in a sprint, often measured in story points. Its recent history can help plan the next sprint.
Vendor Lock-In
Vendor lock-in means switching providers becomes difficult or costly because of the tools, data, or contracts tied to the current provider.
Vercel
Vercel is a website deployment platform that builds and hosts websites and can provide preview versions for review.
Version Control VCS
Version control is a shared, time-stamped history of changes to a project. It lets a team collaborate without losing earlier work.
Virtual Machine VM
A virtual machine acts like a separate computer but runs on shared physical hardware.
Virtual Private Network VPN
A VPN (virtual private network) encrypts traffic between your device and a company network or VPN provider.
Visual Studio Code
Visual Studio Code is a code editor that helps developers write and inspect files, run tools, and work with Git in one place.
Vue
Vue is a JavaScript framework for building browser interfaces from reusable components.
Vulnerability, Exploit & Patch
A vulnerability is a security weakness; an exploit is a way to use it; a patch is a software fix.
Web Traffic
Web traffic is the flow of requests and data between visitors and a website or online service.
Webhook vs API
An API lets one system ask another for information or an action. A webhook lets a system send an update when something happens.
Website Deployment Platform
A website deployment platform builds a site from its source files, puts it online, and can create preview versions for review.
WebSocket
A WebSocket keeps a two-way connection open between an app and a server, letting either send updates at any time.
Windows
Windows is Microsoft’s operating system family for personal computers and servers.
Wireframe vs Prototype
A wireframe sketches a screen’s structure; a prototype lets people try a proposed interaction before the finished product is built.
Zendesk
Zendesk is a platform for receiving, organising, and answering customer support requests.
Zero Trust
Zero trust means checking each request to use a protected system, even when it comes from inside a company network.
Zero-Day Vulnerability
A zero-day is a newly discovered software weakness that attackers could use before a fix is available.