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 North America and Australia), 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 most importantly intelligence. Common use of the unmodified name "collie" in some areas is limited largely to certain breeds – the name means Rough Collie by default in parts of the United States, and Border Collie by default in many rural parts of Great Britain. Many collie dog types do not actually include "collie" in their name – for example the Welsh Sheepdog.