Three reel - The three-reel machine is the most popular and common type of slots. The machine has three reels that stop individually. Payouts are then awarded for winning combinations of symbols.

Five reel- The five-reel machine is very much like the three reel mentioned above, except it has two more lines. Certain five-reel slots payout on less than five matches.

Payline - This is the line that the matching symbols have to line up on to hit the jackpot. Different machines will have different amounts of paylines, but you don't always have to use all of the paylines on the machine. So, you could insert two coins to play two lines on a five-line slot machine.

Most machines have an individual payline with three reels. Some machines allow you to make bets with more than one coin at a time, but that wager will all go to one payline. Sometimes, a three-reel machine will allow for three paylines.

There could be up to 15 paylines on a five-reel slot machine, some of them even being diagonal. You should check into the payline options at your machine before placing any wagers because they can vary.

Progressive jackpot - When the jackpot is always going up, this means that it is progressive. Some slot machines will raise the jackpot periodically, like on each spin, another 10 cents is added to the pot. There are not many machines out there with progressive jackpots though. Most have a fixed limit.