The Australian Shepherd, often known simply as the "Aussie", is a medium-sized breed of dog that was, despite its name, developed on ranches in the Western United States, during the 19th century.
There are different theories regarding the association of the breed with Australia, but there is no consensus on why it was adopted. Genetic research has found that Australian Shepherds and Border Collies are closely related to each other; both are slightly more distantly related to other kinds of Collies and to Shetland Sheepdogs.
Aussies rose in popularity with a boom in Western riding, after World War II. They became known to the general public through rodeos, horse shows, and Disney movies made for television.
For many years, Aussies have been valued by stockmen for their versatility and trainability. They have a similar look to the popular English Shepherd and Border Collie breeds. While they continue to work as stock dogs and compete in herding trials, the breed has earned recognition in other roles due to their trainability and eagerness to please and are highly regarded for their skills in obedience. Like all working breeds, the Aussie has considerable energy and drive and usually needs a job to do. It often excels at dog sports such as dog agility, and frisbee. They are also highly successful search and rescue dogs, disaster dogs, detection dogs, guide dogs, service dogs, and therapy dogs. They are considered the 17th-most popular dog breed in the United States.