Terrier is a type of dog rather than a single breed. The name comes from the Latin terra, meaning earth, because these dogs were developed over several centuries to hunt rats and foxes, often by following them into burrows. Dozens of breeds carry the label, and many adoptable terriers are mixes of Jack Russell, Rat, Cairn, Schnauzer or Chihuahua lines, so a listing's label is a starting point rather than a guarantee.
Most are small to medium, roughly 10 to 35 pounds, with wiry or smooth coats and a confident outlook. They tend to be loyal and affectionate, but barking, digging, chasing small animals and a stubborn streak are common. Many live 12 to 16 years, so adopting one is a long commitment to daily activity, secure fencing or a leash, and patient training.