https://training.github.com
Github’s official git cheat sheets! Handy for remembering the everyday commands you’ll use.
https://learngitbranching.js.org
Confused or intrigued by git’s branch system? That just means you’re human! It’s one of the deepest parts of git, but also arguably the most powerful. Understanding the branch model gives you git superpowers, and this tutorial gives you a way to learn git branches in a visual, intuitive way.
https://git-school.github.io/visualizing-git
Another tool for exploring git visually. This one is more of an open-ended sandbox than learngitbranching.js.org
https://github.com/jlord/git-it-electron
A desktop application that helps you learn git through challenges you have to solve. It has a series of levels, each requiring you to use git commands to arrive at a correct answer.
https://github.com/Gazler/githug
If you liked git-it, Githug is another puzzle-based tutorial designed to give you a practical way of learning git.