Humans produce only one type of hair, each strand from an individual follicle. In a cat, outer "guard," or primary hairs also grow individually from separate follicles; long and rigid, they keep the feline warm and dry. The more numerous secondary hairs of the undercoat, in contrast, grow in clusters from single follicles. This dense, insulating layer is close to the cat's skin and consists of both shorter, bristly "awn" hairs and soft, wavy "down" hairs. Depending on the cat's environment, the double-layered coat works like household insulation to prevent warmth from escaping when it's cold or entering when it's hot.

Cat fanciers give out ribbons for perfectly patterned coats. For a feline that must survive in the wild, though, coat patterns are a hide-saving form of protection. With the exception of the cheetah, which has a spotted coat that is easy to detect on open plains, wild cats dress in one basic style: camouflage. The stripes, spots or blotches help them blend into their environment by obscuring the distinct outline of their bodies. Typically, all cats within a wild species will have similar patterns — a thousand lions will share one basic look. Any group within a species that deviates has evolved a better disguise for its regional habitat; leopards living in jungles, for example, differ in appearance from those residing in high, snowy mountain ranges.

The earliest ancestors of domestic cats are said to have borne color-banded coats that helped them blend in with their surroundings. But as domestication lessened, the need for hunter's camouflage, mutations to solid colors such as red, black and white began to occur. And once cats with these mutated colors started crossbreeding, the color pattern palette burgeoned into countless variations.