From BlenderWiki

[edit] Introduction

The user interface is the vehicle for two-way interaction between the user and the program. The user communicates with the program via the keyboard and the mouse, and the program gives feedback via the windowing system.

If you are new to Blender, you should get a good grip on how to work with the user interface before you start modeling. The concepts behind Blender's interface are specifically designed for a graphics modeling application and the vast array of features are different and differently grouped from other 3D software packages. In particular, Windows users will need to get used to the different way that Blender handles controls such as button choices and mouse movements.

[edit] Blender's Interface Concept

This difference is one of Blender's great strengths. Once you understand how to work the Blender way, you will find that you can work exceedingly quickly and productively. Some features are familiar, like the top menu bar of "File", "Add"..."Help". However, many other features are quite unheard of in most (if not all) other applications. For example:

• Blender windows cannot overlap and hide each other, one exception being a small number of mini-floating panels which are transparent, fold-able, small, and dock-able.
• Blender relies heavily on keyboard shortcuts to speed up the work.
• Blender's interface is entirely drawn in OpenGL and every window can be panned, zoomed in/out, and its content moved around.
• Your screen can be organized exactly to your taste for each specialized task and this organization can be named and memorized.

These key differences (and many others) make Blender a unique, powerful, and very nimble application, once you take the time to understand it.

The interface can be broken down into several key areas: Windows, Contexts, Panels, and Buttons (controls). For example, The Button window contains Context buttons which show different groups of Panels and the Panels each show groups of Buttons. These principal areas are discussed on the following pages.

[edit] Subpages

1. Buttons and Controls
2. Configuration
3. Contexts
4. Keyboard and Mouse
5. Menus
6. Panels
7. Scenes
8. Screens
9. Window system
10.    Arranging frames
11.    Console window
12.    Headers
13. Window types