A muster or a roundup (US) is the process of gathering livestock. Musters usually involve cattle, sheep or horses, but may also include goats, camels,buffalo or other animals. Mustering may be conducted for a variety of reasons including routine livestock health checks and treatments, branding, shearing, lamb marking, sale, feeding and transport or droving to another location.

Mustering is a long, difficult and sometimes dangerous job, especially on the vast Australiancattle stations of the Top End, ‘The Falls’ (gorge) country of the Great Dividing Range and the ranches of the western United States. The group of animals gathered in a muster is referred to as a “mob” in Australia and a “herd” in North America.