A changeup is a type of pitch in baseball. The changeup is the staple off-speed pitch, usually thrown to look like a fastball but arriving much more slowly to the plate. Its reduced speed coupled with its deceptive delivery is meant to confuse the batter's timing. It is meant to be thrown the same as a fastball, but farther back in the hand, which makes it release from the hand slower while still retaining the look of a fastball. A changeup is generally thrown 8–15 miles per hour slower than a fastball. If thrown correctly, the changeup will confuse the batter because the human eye cannot discern that the ball is coming significantly slower until it is around 30 feet from the plate. For example, a batter swinging at the ball as if it were a 90 mph fastball when it is coming in at 75 mph means he is swinging too early to hit the ball well, making the changeup very effective.
Other names include change-of-pace, Bugs Bunny change-up, the dreaded equalizer and change. The changeup is sometimes called an off-speed pitch, although that term can also be used simply to mean any pitch that is slower than a fastball. In addition, before at least the second half of the twentieth century, the term "slow ball" was used to denote pitches that were not a fastball or breaking ball, which almost always meant a type of changeup. Therefore, the terms slow ball and changeup could be used interchangeably.