A skateboard is a term that refers to a thin, wooden or plastic deck with pairs of wheels on which one stands and pushes oneself by pushing along the ground with one foot. The other foot is used for balancing oneself. The word "skateboard" came from the name given to the equipment used by surfers before it was invented by Rodney Mullen in 1975. He called his invention "sidewalk surfboards". You can say that skateboarding is a form of recreational activity that uses a board with metal wheels attached to its bottom surface and a set of plastic or rubber boots attached to its top surface. This allows the rider to walk up any slope or curb without falling off because the ankle support provided by the boots prevents them from slipping out from under him. Skateboards are commonly used by children but also have many adult users who enjoy playing this sport at parks where they won't be hurt if they fall. There are many types of skateboards, depending on the purpose for which it is being used: cruiser boards are designed for cruising around town, while vertigo-inducing boards are designed for doing tricks at high speeds. There are also hybrid boards that combine the two purposes.