From source files to a live site
A team keeps its website files in a repository and connects that repository to a website deployment platform. When the files change, the platform can build a new version, deploy it, and host the result. The repository keeps the source files and their history; the deployment platform makes the built website available to visitors.
The platform can also give reviewers a preview link for a proposed change. This opens a separate version of the site so the team can check it before the change reaches the public production site. Some teams approve a change before publishing it; others publish automatically.
Check which version you are viewing
A link may open a preview or the live site. Check which version it shows when reviewing a change or reporting a problem. A successful deployment means that a version went online, but it does not prove that its content is correct or that important tasks, such as checkout, work.