Theme park is an outdoor entertainment center that offers rides, games, exhibitions, and shows based on one or more special ideas, or themes. The use of themes is the main difference between a theme park and a traditional amusement park. An amusement park offers many kinds of recreation, such as roller coasters, Ferris wheels, carrousels (also called merry-go-rounds), and games, including shooting galleries. A theme park offers recreation with themes, such as wildlife, space travel, the movie industry, a specific location, or a historical period. In an amusement park, customers must pay for each game, ride, or other entertainment separately. In a theme park, customers usually make a single payment to enter, and then they can enjoy all the rides without further charge.