This section assumes that you understand the basics of working with Git. If you don't (or it's been a while), see the Quick and dirty version control and Git introduction section.
Tim Pope's vim-fugitive is a plugin that makes sure you don't need to leave Vim to interact with Git. Since you're editing the files in Vim, you might as well take care of dealing with version control of said edits in the editor. The plugin is available from https://github.com/tpope/vim-fugitive.
A lot of the commands vim-fugitive provides are a mirror of external Git ...