You may be confusing git with GitHub.

git is a version control tool that lets you keep and manage a history of the files you are editing

GitHub is a website (not directly affiliated with the group maintaining git) that lets you upload, backup, and share your code using the format used by the git tool.

source control just refers to software to manage your source code in some form. git is the most popular tool of its kind, but there are others, for example mercurial.