Slot machines have been here entertaining and rewarding players for years now. From a simple box equipped with spinning drums and a lever, these products evolved into fantastic machines that never cease to amaze fans with their innovations and features. First, players were introduced to jackpots and then to linked jackpots and then everything was topped with progressive ones. Additionally, the graphics on the games has been constantly improving, whereas the bonus games get more unique with each newly released title. With time, moreover, traditional slot machines aside from land-based casinos started being offered at online casinos as well, forming one of the most popular category of online casino games. Providers are well aware of players’ affection towards such machines, thus launch breath-taking products on regular basis, whereas operators promote them with all kinds of bonuses and promos such as cash bonuses, no deposit bonuses and free spins. Even though all these offers are relatively similar when it comes to their rules, you can read an example of no deposit bonus terms and conditions here, they provide different benefits nonetheless. Therefore, it’s easy to conclude that the magical world of slot machines is much more than spinning of reels; quite on the contrary, it’s a world full of magical creatures, free cash, bonus features, sound effects and what not. In order to give you a better insight and inform you about all crucial stuff when it comes to online slots, we prepared this guide that features thorough information about providers that develop such games, different types of reel machines, their special features and payouts. Top Slot Machine Developers Even though putting this topic first on the list may seem unusual, online players know that providers are a key aspect when it comes to slot machines. Games by top companies are always innovative, exciting to play and rewarding. Therefore, knowing what those providers are is crucial to finding state of the art slot machines. Several market players that must be mentioned in this paragraph are Playtech, Microgaming, NetEnt, BetSoft and IGT. Nonetheless, there are other developers such as NYX, Realtime Gaming, Leander Games and Elk Studios that also bring lots of top notch slot machines in the industry’s overall selection that deserve players’ attention. Types of Reel Machines Many people, who aren’t familiar with slot machines, take the liberty to comment that all such games are the same. However, that can’t be any further from the truth since there are several different types of reel games. First, we have the classic slots that often feature only three reels and simple design. Just like their name suggests, these online slots resemble the traditional machines in both features and design. Then, we have the widely popular video slots. These fan favourite products always come equipped with amazing graphics and animations that take players to new worlds of mystery and action. It can be said that the largest number of slots on the market, at the moment, belongs to this category. Video slots, however, in terms of graphics and graphic effects have a strong competitor in 3D slots; with 3D characters, symbols and background, these machines provide a truly amazing gaming experience. Finally, it’s important to mention progressive slot machines; this type of games comes with progressive jackpots that grow with every single wager, meaning they often offer multi-million prizes that can be won with a single spin. Slots Features When it comes to slots, there are numerous features that have the power to completely change the overall experience and make it either more exciting or pretty dull. These features are important to players and therefore they always pay attention to them. Here are the top ones and how they can differ. Number of reels – slots can have anything between three and five reels; however, lately providers know to surprise customers with slots that have six, seven or even more number of reels as well; Number of paylines – the more paylines, the bigger chances to hit a winning combination. Slot machines can have a single payline or as many as 100. Nonetheless, the most commonly seen number of paylines varies between five and 30; Special symbols – aside from standard symbols, slots may feature some special features such as wilds, scatters and bonus symbols too; Bonus games – these are probably the most important slot features. Regardless whether a slot comes with a free spin feature, a pick and win feature or anything similar, when these are triggered players can hope for a juicy prize at the end of the session; Special features – these are features that make the game special and unique; they can be represented by Avalanche symbols, expanding wilds, sticky wilds and all other kinds of solutions. RNG, RTP and Fairness Not a single guide on online slot machines should go without, at least, a brief explanation about random number generators (RNGs), return to player percentage (RTP) and fairness. Namely, RNGs are responsible for giving out the outcomes of the games and they are often audited by independent organisations that make sure everything works properly. Therefore, games whose RNG is tested and approved by reputable auditors like eCOGRA and TST Labs provide 100% random and unpredictable results. RTP, on the other hand, reveals how high the house edge is and how rewarding the machine is. The higher the RTP the better chances of winning players have. Leading providers usually provide RTP reports that help customers build an image of what to expect while playing the slot. In general, reel machines with RTP of over 95% are considered to be the best ones in comparison to games with RTP of 90% and below.