Materials describe how an object reflects or transmits light. Within a material, maps can simulate textures, applied designs, reflections, refractions, and other effects. (Maps can also serve as environments and projections from lights.)
The Material Editor is the dialog you use to create, alter, and apply the materials in your scene. The available materials depend on the active renderer.
Image by Michael McCarthy
Left: Only a neutral, gray material applied to objects
Right: Realistic materials applied to the scene, including transparent glass, scenery, and a snowfall