Torbie, short for tortoiseshell tabby, describes a coat, not a breed. A torbie blends patches of black-based and orange-based color with tabby stripes or swirls, often with the M mark on the forehead. Brown, dilute blue-and-cream and silver versions all exist, and a torbie with plenty of white is sometimes called a caliby.
Most are domestic shorthairs or longhairs, usually 6 to 14 pounds, and many live 12 to 18 years. Shedding is moderate, so weekly brushing helps, especially in a small apartment where fur collects fast. The "tortitude" reputation is folklore rather than science, so judge each cat by how she acts, not by her color, and match her energy to your daily routine.