A term Sim slots (or Simulation slots) is usually used to describe online slots and differentiate them mechanical slot machines you can play in brick and mortar casinos.
But as a matter of fact, sim slots don't differ much from casino slots, they're just an on-screen representation of the real slot machines, except for the fact that you can play them in the privacy of your own home or office.
Even though sim slots is only a simulation, the logic and rules are all based on those of the slot machines at an actual casino. Of course, there are physical differences, but in reality there is no technical difference between sim slots and land-based slots when it comes down to the way they work.
In the old days, slot payouts were determined by the number of reels and the number of stops on each reel. Modern slot machines, whether online or in land based casino, are governed by random number generators.
Since each casino software provider tries to attract players by the wide selection of one arm bandits, there are hundreds of different types and variations of sim slots - single line, three line, 3 or 5 reel, progressives, bonus games and many others.
Progressive sim slots are linked in a bank of machines so that a certain percentage of every bet goes to the progressive jackpot pool. This jackpot pool belongs to a group of different online casinos.
The special prizes is waiting for you if you get a special symbol combination or collected certain symbols. If you do, you will enter a bonus round, which can be anything from Wheel of fortune to second screen.
Usually a player have to bet maximum coins to qualify for the bonus round. Find bonus sim slots here.