README file

In short: The README is the front page of a project: a text file (usually README.md) that explains what the project is, how to install and use it.

In more detail: GitHub and GitLab show the README automatically on the project page. It is often the first thing users and recruiters see and saves many questions.

In detail

• Content: name and short description, installation, usage with example, requirements, licence, contact, notes on contributing.
• Format: Markdown (.md) with headings, lists, code blocks, images, badges.
• Other files: LICENSE, CONTRIBUTING.md, CHANGELOG.md, .gitignore.
• Tip: put a “quick start” with three commands at the top.
• Maintain: outdated instructions are worse than none.

See also: GitLab, Code comments