git-cola is a powerful Git GUI, with a slick and intuitive interface.

It comes with excellent documentation https://git-cola.readthedocs.io/
and a plethora of useful functionality, including:

- direct integration with git subcommands
- git-tag, an interactive tree & commit history browser
- an integrated file browser to view any file at a given commit
- an interactive rebase and merge facility
- search comimits, and grep content
- partial file commit that is a delight to use