The technology of slot machines has also changed a lot over the years. The classic mechanical designs have been almost completely replaced by computer-controlled machines. But the game has remained the same. The player pulls a handle to rotate a series of reels (typically three) that have pictures printed on them. Winning or losing is determined by which pictures line up with the pay line, a line in the middle of a viewing window. If each reel shows the same winning picture along the pay line, you win (certain single images are sometimes winners as well). The amount you win -- the payout -- depends on which pictures land along the pay line.