.GITKEEP File Extension
What is a GITKEEP file?
A GITKEEP file is an empty file that Git users create so that a Git repository preserves an otherwise empty project directory. By convention, empty directories that contain no files are not committed to Git repositories. However, a single GITKEEP file in a directory causes Git to preserve the directory in the repository.
The file extension ".gitkeep" is not a part of the official Git standard but has come about by convention with some Git users. The extension name is considered a good choice because it is the opposite of .GITIGNORE, which is an official Git file extension that tells Git which files to ignore when committing to the repository.