A slot machine or a fruit machine or poker machine is a type of casino game. The traditional slot machines are coin-operated machines with three or more reels, which spin when a lever on the side of the machine is pulled. The machines include a currency detector that validates the coin which is inserted to play. The player will pull the lever and the machine pays off the player based on patterns of symbols visible on the front of the machine when it stops. With technology slot machines are the most popular gambling method in casinos accounting for about 70% of the average casino's income.

The first online slots appeared in 1996 at two online casinos. Initially they were simple 3-reel slots which is similar to slot machines found in Las Vegas, but with the advent of online video slots machine, there are now hundreds of slots available, many of which incorporate features and bonus rounds.