Tundra is a one stop grasshopper plugin for generating complex noise patterns. Includes noise generators as well as lots of useful methods such as filters, modifiers, combiners, transformations...
Tundra grasshopper plugin implements open source noise library - Libnoise, http://libnoise.sourceforge.net/ all the naming is inherited from this library so the libnoise documentation can be used for tundra as well.
The noise function in this plugin is referred to as module and it represents the variable type which is passed by tundra components. Also module is the same type that underlying Libnoise library uses.
There are two basic ways of using generated noise procedures, by evaluating 3d point with GetValue component or generating bitmaps with NoiseBitmap component. Other than those it is possible to convert noise fields to grasshopper vecor field type by Gradient and Curl components.