A terrier is a dog of any one of many breeds of terrier types. They are named from the Latin word "terra" meaning earth. It refers to their love of digging after their prey (small burrowing mammals). Terriers are typically small, very active and fearless dogs. Terrier breeds vary greatly in size from just to over . They are usually categorized by size or function. There are five different groups with each group having several different breeds. Terriers do not usually tolerate other dogs well. They are descended from dogs bred to hunt and kill rodents. Terriers usually have 'wiry' (stiff hairs like wire) coats that need special care. Examples of terriers include Irish Terrier and the Cairn Terrier.