Git

Git is currently the most popoulat version control system in the world. It was created in 2005 by Linus Torvalds when the Linux Kernel grew out of all existing VCSs. It uses hashing (SHA1) on text-files to be able to compare versions of the same file linewise. It then inserts or deletes lines as needed,and keeps track of all users and different branches.

Working with more than one person on a project, version control systems change everything. And Git is the best.