Diff

A representation of the lines or files added, removed, or changed between two versions of a project.

A diff records how one version differs from another. Text diffs usually mark removed lines with a minus, added lines with a plus, and show nearby unchanged lines for context. If a password-reset edit also changes link expiration, that second edit appears in the diff even when the change summary omits it. Renames, generated files, binary assets, and semantic effects may need other views, so the diff is an inventory of edits rather than a complete explanation of behavior.

Builder example

A diff supports several checks. Machines can reject changes outside an allowed path, scan dependencies, or run tests selected from touched code. A person or review model can inspect a sensitive authorization rule. Runtime tests can establish behavior that the changed lines alone cannot. Smaller cohesive diffs make all of those checks easier to target and failures easier to diagnose.

Common confusion: A diff shows what changed between two versions; it does not judge whether the change is correct or safe. A clean-looking diff can still add a line that breaks a feature, so you read the diff to understand the edit and still run the project to confirm it works.