What's noise?

A texturing primitive
Use it to create "natural" looking textures
No memory/bandwidth requirements
No mapping problem
Very wide variety of effects

Noise is a texturing primitive you can use to create a very wide variety of natural looking textures. Combining noise into various mathematical expressions produces procedural texture.

Unlike traditional texture mapping, procedural texture doesn't require a source texture image. As a result, the bandwidth requirements for transmitting or storing procedural textures are essentially zero.

Also, procedural texture can be applied directly onto a three dimensional object. This avoids the "mapping problem" of traditional texture mapping. Instead of trying to figure out how to wrap a two dimensional texture image around a complex object, you can just dip the object into a soup of procedural texture material. Essentially, the virtual object is carved out of a virtual solid material defined by the procedural texture. For this reason, procedural textures are sometimes called solid texture.