A breakaway rim is a basketball rim that contains a hinge and a spring at the point where it attaches to the backboard so that it can bend downward when a player dunks a basketball, and then quickly snaps back into a horizontal position when the player releases it. It allows players to dunk the ball without shattering the backboard, and it reduces the possibility of wrist injuries. Breakaway rims were invented in the mid-1970s and are now an essential element of high-level basketball.
In the early days of basketball, dunking was considered ungentlemanly, and was rarely used outside of practice or warm-up drills. A broken backboard or distorted rim could delay a game for hours. During the 1970s, however, players like Julius Erving and David Thompson of the American Basketball Association popularized the dunk with their athletic flights to the basket, increasing the demand for flexible rims.