From BlenderWiki

System & OpenGL

This tab gathers more advanced, technical settings.

Solid OpenGL lights

When working in solid view, you can “light” the objects in your workspace with up to three OpenGL light sources. The direction of each source is set by dragging inside the light sphere, and the colors of the diffuse and specular shading are set by clicking on the relevant color swatch and using the pop-up color picker.

Auto Run Python Scripts

When enabled (the default), selecting a script from any menu runs that script. However, Python is a powerful language and if you suspect a virus or get a .blend file from an untrustworthy source, disable this prior to opening the blend file to prevent the script from running.

Win Codecs

Windows only!

Codecs are routines that encode and decode video streams. Enable this to use any codec found in your system. Some codecs can mis-behave, and can falsely assert themselves. If you have one of these pontificating codecs on your system, disable this.

Color range for weight paint

When weight painting, by default we use a colorful gradient to represent weights ranging from 0.0 (blue) to 1.0 (red). If you want to use a different set of colors to represent this range of weight values, enable ColorBand and use the colorband control to set the custom color gradient.

Audio mixing buffer

When mixing audio or using audio in the game engine, this allows you to set aside memory for sound.

Verse

Not always available!

Verse allows multiple users to work on the same blend file. Enter the URL of the Master and your username here. Then use the File » Verse sub-menu to get connected to your buddies.

Keyboard

Enable Emulate Numpad if you don’t have a numerical keypad and want to emulate it (for laptops). If your fat fingers keep pressing the darn caps lock instead of the tab key, disable it.

System

Various system settings. Prefetch frames allows Blender to get anticipated frames into memory, allowing you to work smoother. If you are using the Video Sequence Editor a lot, you might want to increase your MEM Cache Limit. If you are rendering frames on request as a slave, enter the port number to listen for requests on in the Frameserver Port numeric field.

OpenGL

This group of controls allows you to fine-tune how OpenGL displays textures and functions on your system.

Language & Font

International Fonts, when enabled, allows you to choose the GUI language and font (e.g. to have Kanji or Pharsi chars).

If you choose another language than English, you can select which parts of the GUI should be translated – Tooltips, Buttons and/or Toolbox (a good idea would be to only enable tooltips, so that you keep the interface itself in English, as in this manual, but have the small help messages in your native language).