http://docs.unity3d.com/Documentation/Manual/index.html

Unity Manual

Welcome to Unity.

Unity is made to empower users to create the best interactive entertainment or multimedia experience that they can. This manual is designed to help you learn how to use Unity, from basic to advanced techniques. It can be read from start to finish or used as a reference.

The manual is divided into different sections. The first section, User Guide, is an introduction to Unity's interface, asset workflow, and the basics of building a game. If you are new to Unity, it is recommended that you start learning by reading the Unity Basics subsection.

The next section, FAQ, is a collection of frequently asked questions about performing common tasks that require a few steps.

The last section, Advanced, addresses topics such as game optimization, shaders, file sizes, and deployment.

When you're done reading, be sure to take a look at the Reference Manual and the Scripting Reference for further details about the different possibilities of constructing your games with Unity.

If you find that any question you have is not answered in this manual please ask on Unity Answers or Unity Forums. You'll definitely find your answer there.

Happy reading,
The Unity team

The Unity Manual Guide contains sections that apply onto to certain platforms. Please select which platforms you want to see. Platform-specific information can always be seen by clicking on the disclosure triangles on each page.