When you walk onto a casino floor anywhere in the world you will undoubtedly see a wide range of different slot machines. While there are thousands of different slot machines they all fit into one of the categories outlined below. The first two categories are related to the style of jackpot which can be found on all of the other categories.
Games with fixed jackpots have a jackpot that is displayed on the machine that never changes. This is the most common style of jackpot that you will see in most casinos and are always used for slot tournaments both online and offline.
Slots with a progressive jackpot have a top prize that grows as people play. This gives the casinos a chance to offer huge jackpots as the prize pool is funded by players. You can easily identify a progressive slot by the jackpot meter which shows the current prize. To offer even bigger jackpots the casinos now use linked jackpots which links machines in the casino as well as machines at different casinos. The most famous linked progressive is IGT's Megabucks.
These games all have three spinning reels using traditional symbols on round wheels. The games appear to be simply mechanical although his is not the case. They use the same type of RNG used in video slots so every spin is random. Most of the games of this type still have a handle you can pull although most players go for the buttons instead.
The games use a video display rather than having spinning reels. They most commonly have five reels but you can find three, four or even six reel games. You will also see a wide range of line layouts from 5 line to 100 line to 243 Ways. Video slots are slowing taking up more and more space on the casino floor due to their popularity with players.
Bonus Feature Slots
Games with any sort of additional feature other than the reels are known as bonus slots, bonus feature slots or feature slots. You can find both classic and video screen based games with bonuses. Common features include free spins, pick an object and the popular Wheel of Fortune style bonus.