Tool for programmer team

What is a good tool to coordinate a team of programmers efficiently? To give each one a different part of the project is a start, but it needs to get combined at some points to be a working project. Not to debug code you have written was a hint, to see actually bugs as a bug and not as a feature. Some hinted let programmer be on different places, others say put them together on a big table, ... Where can I find more information about that subject? bye R