Collies form a distinctive type of herding dogs, including many related landraces and standardized breeds. The type originated in Scotland and Northern England. Collies are medium-sized, fairly lightly built dogs, with pointed snouts. Many types have a distinctive white color over the shoulders. Collies are very active and agile, and most types of collies have a very strong herding instinct. Collie breeds have spread through many parts of the world (especially Australia and North America), and have diversified into many varieties, sometimes mixed with other dog types. Some collie breeds have remained as working dogs for herding cattle, sheep, and other livestock, while others are kept as pets, show dogs or for dog sports, in which they display great agility, stamina and trainability. While the American Kennel Club has a breed they call "collie", in fact collie dogs are a distinctive type of herding dog inclusive of many related landraces and formal breeds. There are usually major distinctions between show dogs and those bred for herding trials or dog sports: the latter typically display great agility, stamina and trainability, and, more importantly, sagacity.
Common use of the name "collie" in some areas is limited largely to certain breeds—meaning Rough Collie in parts of the United States, and meaning Border Collie in many rural parts of Great Britain. Many collie dog types do not actually include "collie" in their name (see Welsh Sheepdog at right).