A material defines how the layer and its associated surface object appears. It defines how it interacts with lights, how it reflects light back to the view, and how it blends in with the rest of the scene. You can choose one of four shader types to set the basic material properties for a given layer and choose from a wide selection of blending modes to define how the current layer is blended with the scene element lying behind it (with respect to the view).
In addition, each material node has five input tabs, or channels, that you can use to assign one or more sources to apply textures to an object. The main material channel defines a layer's base material and texture mapping, and is always used. You can optionally connect sources to the other inputs on the material node to define a bump map, as well as radiosity, reflection, or refraction environment maps, depending on the shader type selected.
Textures are 2D images that can be wrapped around an object's surface, much like a piece of paper wrapped around an object. The information displayed on the object's surface depends on the type of texture map used. In bump maps or normals maps, RGB or luminance values are used to give the surface the illusion of peaks and valleys. In radiosity maps, the object appears to blend in the source image's radiosity. This is useful for creating realistic lighting effects without the high rendering cost associated with raytracing or radiosity.