Calico is a coat pattern, not a breed. A calico cat has three colors, white plus patches of black and orange, or soft gray and cream in the dilute version, and the pattern turns up in domestic shorthairs and longhairs as well as many pedigreed breeds. Because the orange and black color gene sits on the X chromosome, nearly every calico is female; the rare males usually carry an extra X chromosome and are typically sterile.
Most calicos waiting in shelters are domestic shorthairs, so their size, coat and health follow ordinary house cats rather than any single breed. Folklore credits calicos with sass and good luck, but research has not shown that coat color predicts personality. Meeting the individual cat, and seeing how it behaves with people and other pets, tells adopters far more than its patches ever will.