The `.gitignore` file tells Git which files or folders in a project it should leave out of its change list. It is like a note saying that temporary scraps do not belong in the shared project notebook.
A project may use it to ignore generated files, local settings, or downloaded packages that can be recreated. This keeps the shared history focused on files the team intends to track.
Ignoring a file does not delete it from your computer or make it private. If a file was already tracked by Git, adding its name to `.gitignore` may not remove it from the saved project.