No self-respecting circus is complete without a nattily dressed man or woman stepping into the ring to shout the program and keep the crowd excited. The ringmaster, formerly called the riding master from the circus' equestrian history, was an important part of the early circus. While not technically an act, it's a tradition that has continued throughout the modern circus.
While ringmasters often interact with the clowns in present-day circuses, they're really there to present the acts to the audience. Early ringmasters took on the job of emcee, but they were also responsible for keeping the horses at a steady gait while performers did acrobatics on the horses' backs. Hence we often see the ringmaster wearing the red coat, white pants and high boots of an equestrian captain. Ringmasters in early circuses struck their whip on the ground to prompt the horses. The clown, on the other hand, might get a more direct hit.