When you type git commit, Vim starts and opens a commit buffer. This plugin improves the commit buffer. committia.vim splits the buffer into 3 windows; edit window, status window and diff window. You no longer need to repeat scroll and back to the former position in order to see a long commit diff. If the width of Vim window is too narrow (160 characters by default), committia.vim falls back to single column mode, which has 2 windows; edit window and diff window.