The collie is a distinctive type of herding dog, including many related landraces and formal breeds. The breed originated in Scotland and Northern England. The collie is a medium-sized, fairly lightly built dog, with a pointed snout. Many types have a distinctive white pattern 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 with mixture from other dog types. Some collie breeds have remained as working dogs, used 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 AKC has a breed they call "Collie", in fact collie dogs are a distinctive type of herding dog including many related landraces and formal breeds. There are usually major distinctions between show dogs and those bred for herding trials or dog sports. They 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 – such as to the Rough Collie in parts of the United States, or to the Border Collie in many rural parts of Great Britain. Many collie types do not actually include "collie" in their name.