From BlenderWiki

Manual - Blender 2.44

[edit] Help system

Blender has an interesting mix of built-in, loadable, and web-based help, all accessed with Blender. All of the help is accessed through the Help menu at the top of the page in the User Preferences window header. Of course, any web-pages can be saved to your local hard disk or printed using your web browser for off-line viewing. We use web-based help so that we can bring you the latest up-to-date help.

[edit] About Blender

Displays the splash screen image, identifying the package and version.

[edit] Blender/Python Scripting API

Web-based help pages describing the application programming interface (API) that Blender exposes to Python. Python is a general programming language that can do many things on its own. In order for it to do things inside Blender, it has to access Blender functions, like creating objects, moving them, etc. Python does this by calling on specific Blender API calls, like ob.setLocation to change an object's location.

[edit] Getting Started

Web-based help pages listing specific links to official sites maintained with fool-proof, easy tutorials that can help you get started and comfortable using Blender.

[edit] HotKey and MouseAction Reference

Internal There's an old adage among Blender users:

Blender makes extensive use of hotkeys to allow you to quickly perform common actions, like R to Rotate the selected object. This internal page tells you what all those keys do, separated into Arrows, Letters, Mouse actions, Numbers, etc. It has a Search Function, so if you vaguely know the term for what you want to do, you can search for the hotkey to find out how to do it.

[edit] ID Property Browser

Internal For all the various kinds of objects in your .blend file, this screen allows you to find them (starting at the Scene level) and drill down to inspect their properties.

[edit] Manual

Web-based Brings you to the main table of contents page of the wiki.

[edit] Python Scripting Reference

Same as Blender/Python Scripting API

[edit] Release Notes

Web-based A page listing all the Release Notes, telling you what has changed and new features added to Blender, back several versions. The release notes provide you with a quick explanation of "what's new", frequently along with examples and demonstrations and movies/images.

[edit] Scripts Help Browser

Internal This window allows you to choose a script (from your \scripts directory) by category, and shows you the help information embedded within the script. Use this to find out more about what these custom Python scripts do, and how to use them.

[edit] Tutorials

'Web-based Lists simple, step-by-step tutorials that can provide you with easy-to-follow directions on how to use Blender. Please also visit the wiki Tutorials page.

[edit] Websites

Web-based Lists frequently accessed websites related to Blender and its development.

[edit] System

With a 3D View window active, clicking Benchmark enables you to benchmark three different actions in Blender. The resulting statistics, particularly the 'operations per second (ops/s) is useful for comparing the performance of Blender across different machines. For a more robust benchmark, refer to the [official Benchmark site.]

System Information creates an info.txt file which lists various key properties of your system and Blender, useful in diagnosing problems.

Manual