Unicorn is a utility for Sitecore that solves the issue of moving templates, renderings, and other database items between Sitecore instances.
This video gives a great introduction to what it is and how it works. It’s for Unicorn 2 and Unicorn in now on version 3, but it’s still a good starting point.
More information on unicorn can be found at. https://github.com/kamsar/Unicorn