Git

Open source distributed version control system

Learning to use Git
https://uoftcoders.github.io/studyGroup/lessons/git/collaboration/lesson/

GIT Essentials Training (Lynda.com - account required)
https://www.lynda.com/Git-tutorials/Git-Essential-Training-Basics-REVISION-2019-Q1/5030978-2.html 

GitHub Collaboration Tutorial
https://www.youtube.com/watch?v=jLWZaFzPS6Q