Git is well-known and lately has become a popular version control system. Unlike SVN, it's decentralised and lets you work locally, without any internet access, which can save you precious time more often than you think.
On the other hand, it beats Mercurial with its massive number of functionalities, which may be sometimes overwhelming for some developers.
For a lot of dev teams, starting to work with a brand new system raises a lot of questions, the most important being how to setup a good workflow.
There are many opinions on this subject, however, and it takes time to wade through all of them. The "Forking with feature branches workflow" is one workflow that has been adopted by a very large crowd of open-source developers, including us.