The name of "terrier" comes from the latin word "terra"=ground and refers to dogs which hunt in ground or in burrow, more certain. The terriers was specialized to chase the prey from the burrow, or for catching and killing it. The big sized ones were used also as watchdogs. The small sized breeds named also "dwarf and toy terriers" (Silky Terrier and Yorkshire Terrier) are appreciated as companion animals.
The classic terriers, with short or long legs, are tenacious, brave dogs, aggressive against predators. Because their inborn hunter instincts, they can't be trusful around small animals, if they weren't proper socialized since an early age. They are dynamic, jolly, pretty noisy dogs with a timeless tendency to dig.
The terriers of Bulldog type, like Bull Terrier, Staffordshire Bull Terrier, American Pitbull Terrier were created through the crossbreeding between terriers with dogs used for bull fights and were used mainly for dogs fights and other bloody sports. Even they have the reputation of fierce animals, generally they are vrey friendly with people, even more than the classic terriers. Due to their love for children, in England the breed Staffordshire Bull Terrier is nicknamed "Nurse dog".
The Bull Terriers are often aggresive against other dogs.
Big sized terriers are used as watchdogs.
The terriers are intelligent, understand easily what are required, can be trained pretty easily, even sometimes can be a little stubborn. They have a lot of energy and like to be always active. They must be socialized since pups with other animals from household, for not chasing them when they'll grow up.
They accommodate easily to the offered conditions. Generally, they like to dig.