You can use textures to precisely control a variety of your objects' attributes, from bumps and ridges, to transparency, reflection, and environment. Using textures to drive these attributes lets you clearly define where they are applied and to what degree. The texture acts as a map that the attribute follows.
You can drive practically any shader parameter by connecting a texture to its input port in the render tree. If necessary, you can use the conversion nodes to convert a color to a scalar, or a Boolean, or something else. You can also use the Color to Scalars or RGBA Split nodes to use different channels in a texture image to drive different parameters in a render tree.
For example, you can use a texture to vary the specularity, reflectivity, or glossiness across the surface of an object as controlled by an image and its projection.
The sections that follow go into more details about some of the common uses of textures to control bump, displacement, transparency, reflectivity, and reflection.
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