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