Repetitive behaviors in autism are part of autism. These purposeless behaviors are almost always a symptom of autism.
Repetitive behaviors include lining up of toys, spinning objects or opening and closing drawers or doors, rocking etc.. Repetitive behaviors can also involve saying, thinking about or asking about the same thing over and over again. In rare cases, behaviors can automatically be dangerous. They can become a problem though when they get in the way of ordinary activities or make it tough to get in school or work.