Fads are objects or activities that are popular with a group of people over a short period of time. Fads are also known as crazes. Fashions are a related phenomenon and are defined as objects or activities that become popular within larger groups over longer periods of time. Fashions are also known as trends. Researchers argue that people follow fads and fashions as a result of both informational social influence (where they incorporate useful information from others about what is acceptable and desirable) and normative social influence (where they adopt the acceptable behavior or desired object so that they themselves are accepted and liked by others). By following fads and fashions people can also assert their identity.