Tuxedo describes a coat pattern, not a breed: a bicolor cat, usually black and white, with a white chest that looks like a shirtfront and often white paws, chin or a facial blaze. Grey-and-white Tuxedos exist too. The pattern comes from white spotting variation in the KIT gene, and because it isn't sex-linked, males and females are about equally common.
Most Tuxedos are domestic shorthairs, though the pattern also shows up in breeds like the Maine Coon and British Shorthair. Color doesn't set personality, so you'll meet quiet lap cats and busy climbers alike. A typical Tuxedo weighs 6 to 14 pounds, sheds moderately and can live 12 to 18 years, so adopting one is a long commitment worth planning for.