Skateboarding originated in the 1950s and grew in popularity in the early 1960s. The invention of urethane wheels improved skateboarding. The ollie is a fundamental trick where the board stays under the feet and is leveled in the air by popping the back foot and sliding the front foot. Popular tricks include kickflips, heelflips, and various grinds and flips. Stances include regular, goofy, and mongo. Proper landing technique is important to avoid injury.