Git is a distributed version control system that allows for both local and remote collaboration on code. It provides advantages like speed, simplicity, integrity, and support for parallel development through features like branching. Common Git commands include git init to start a new repository, git add to stage files, git commit to save changes, git push to upload local work to a remote repository, and git pull to download remote changes. GitHub is a popular hosting service for Git repositories that provides a graphical interface and social features.