GitHub is a code hosting platform that allows users to store and manage code as well as track changes through versions. It provides a graphical interface for Git repositories along with features like issue tracking, code review, notifications, and security alerts. To use GitHub, a user creates an account, verifies their email, installs the GitHub Desktop app to manage local repositories, and pushes code changes to the online repository where others can see them. Advanced features include creating branches to isolate work and pull requests to review changes before merging them into the master branch.