.GITIGNORE File Extension
What is a GITIGNORE file?
File used by Git, a version control system used for storing source code; contains a list of files that should not be committed to the Git source code repository; often used for omitting non-text (binary) files, OS files (e.g., .DS_STORE and Thumbs.db files), and temporary files from the repository.
GITIGNORE files can be created for any subpath within the project directory structure so that the rules apply specifically to that path.
NOTE: GITIGNORE files are stored in plain text format and can be edited with a text editor.