What is the primary purpose of a .gitignore file in Git?

The primary purpose of a .gitignore file in Git is to specify files that should not be tracked. This is important for a number of reasons, including preventing sensitive information (like API keys or passwords) that shouldn't be shared from being included in the version control history. Additionally, it prevents temporary files, logs, and build artifacts—often generated in development environments—from cluttering the repository. By listing these types of files and directories in the .gitignore file, developers can maintain a clean repository that focuses only on the necessary project files, improving both the functionality and clarity of the version control history.

Files specified in the .gitignore are effectively ignored by Git, meaning they won't appear in Git's status, and will not be included in commits. This provides a streamlined experience for collaborating on projects, ensuring that only relevant and intentional files are shared across contributors.