Habitat and the tools and processes in it is a Sitecore solution example built on the Helix architecture principles.
The architecture and methodology focuses on:

• Simplicity - A consistent and discoverable architecture
• Flexibility - Change and add quickly and without worry
• Extensibility - Simply add new features without steep learning curve

For getting started, please check out the Documentation.
For more information on Helix, please go to helix.sitecore.net.