The Ollie is a skateboarding trick that was invented in the 1970s by Alan Gelfand. It involves the skater jumping and using their back foot to kick the tail of the board, causing it to pop up into the air. The skater then jumps onto the board while it is in the air and lands back on the ground. This trick has become a staple of skateboarding and is often used as the basis for more complex tricks.