Git is a one of many version control tools out there, for example Subversion (SVN) and Mercury you also have the expensive IBM Synergy (formerly known as Telelogic). GIT is a decentralized repository, meaning that you have locally the whole repository. So when there is a VPN issue with the Synergy server, productivity stops.
For both solutions, it’s important to have a build manager / merger. So that one person is in charge of the collecting of code from each developers branch into the release branch.
For GIT, there are several GIT services available like Bitbucket, GitHub and GitLab CE. I’m using both GitHub for open-source projects and GitLab for more private projects.