Coding is simple and great if it's just you working on the code. It is getting much more complex when a whole team or even several teams are working on the code base. You want to be sure, that everybody knows about code changes, the quality is the same all over the code base and a merge shouldn't stop the whole team from working. Atlassian's tools can help you out.
This presentation shows how you can use Stash and Bamboo to happily code together in a team. You don't have to worry about broken builds on your master branch or that your graduate accidentally merges his changes that get automatic deployed. Everybody understands each part of the code base and the code got reviewed before it hits your master branch.