If a file is already tracked by Git, what happens if it is added to the .gitignore file?

When a file is already tracked by Git, adding it to the .gitignore file does not affect its current status as a tracked file. The purpose of the .gitignore file is to specify intentionally untracked files that should be ignored by Git. However, if a file is already being tracked, Git will continue to track changes to that file, regardless of the entries present in .gitignore.

Therefore, the correct understanding is that the addition of a file to .gitignore does not retroactively cause Git to ignore it. Instead, it remains under version control, and any subsequent changes to the file will still need to be manually staged and committed. Thus, the file will continue to be monitored by Git, and changes will be tracked and included in future commits unless the file is explicitly untracked using the appropriate Git commands (like git rm --cached <file>).