According to About.com, maracas make sound through the rattling of the small objects they contain inside, typically stones, beads or beans. Maracas are classified under the instrumental category of solid or sealed objects known as idiophones.
The word "maraca" likely originates from the Araucanian people native to central Chile. The maraca's precise origin is unknown, but similar instruments were used by many ancient peoples. African tribes played drums and other percussion instruments, including rattlers that were similar to maracas. South Pacific Islanders also created maraca-like instruments out of plants with seed pods. In South America, shamans and witch doctors historically used maracas in ceremonies intended to contact spirits.