Git: A distributed version control system.
GitHub: GitHub is a code hosting platform for collaboration and version control. GitHub lets multiple developers work together on projects.
Repository: A gitHubrepository is used to store: Development Projects Folders and Files of any type (HTML,CSS,Javascript,documents,data,images)
Branch: A GitHub branch is used to work with different versions of a repository at the same time. By default a repository has a master branch (a production branch). Any other branch is a copy of the master branch (as it was at a point in time).
Commits: At GitHub changes are called commits.