Mercurial is a free, distributed source control management tool. It efficiently handles projects of any size and offers an easy and intuitive interface. That's what there website says in anyway.
When you start a project you should always backup your code, with HG (Mercurial) you can do this and keep copies of every revision you have made, along with the ability to have many people working from the same source. visit here to see what projects redbrickers are currently working on. If you would like to get your own hg contact an admin!