The Border Collie is a British breed of herding dog of the collie type of medium size. It originates in the region of the Anglo-Scottish border, and descends from the traditional sheepdogs once found all over the British Isles. It is kept mostly as a working sheep-herding dog or as a companion animal. It competes with success in sheepdog trials. It has been claimed that it is the most intelligent breed of dog.

A herding dog, also known as a stock dog or working dog, is a type of dog that either has been trained in herding livestock or belongs to one of the breeds that were developed for herding. A dog specifically trained to herd sheep is known as a sheep dog or shepherd dog.