Fox Terrier usually means the Smooth Fox Terrier or the Wire Fox Terrier, two separate breeds that share a sturdy, leggy build and a lot of personality. Britain developed them to ride along on foxhunts and bolt foxes from their dens, which is why they're mostly white. The tiny Toy Fox Terrier is a different breed, and the name is also used loosely for terrier mixes.
At home, expect a bold, funny dog with a mind of its own and a strong prey drive. Some are scrappy with other dogs, and many dig, bark and jump. Smooths have a short coat that needs a weekly brush. Wires shed little but need regular clipping or hand-stripping, so grooming effort and cost depend on coat type. Both types are small, which makes cold-weather gear worth owning.