A program’s workbench
A program keeps information it is using in RAM, such as an open page or a calculation in progress. The stack keeps track of active steps; the heap stores data the program creates as it runs.
Some programming languages automatically free heap space when they can tell the data is no longer in use. This is called garbage collection, and it also takes time.
When high use matters
High memory use can be normal: a cache saves data so it can be reused quickly. A large task may also need extra space for a while. Teams look for slowdowns, crashes, and memory use that keeps rising. A memory leak means the program keeps data it no longer needs.