IntroductionSlots are the most popular genre of casino games. Many consider slots to be more fun and exciting than other casino games due to the bonus rounds, creative themes, and chance of a large win off a small bet. Unfortunately slots are one of the worst mathematical bets in online casinos with a typical house edge of 3-6%. Nevertheless, slots-only bonuses can be significantly EV+ and worthwhile.Rules and Play3-Reel Slots -- As the name implies, 3-reel slots have 3 reels. If the reels line up according to the listed paytable, you get the corresponding payout. The maximum payout often requires betting maximum coins (usually 3). There are many variations. Some 3-reel slots also have bonus rounds. If a certain symbol or combination of symbols appears, you enter a separate screen where you have the chance of a large win. You may have to pick a box, spin a wheel, or simply click a button.Video Slots -- Standard video slots have 3 rows and 5 reels, for a total of 15 symbols. If you get 3 or more matching symbols, you receive the corresponding win. Wins usually pay from left to right, meaning 3 matching symbols in the first 3 reels is a win, but 3 matching symbols in the final three reels is not.Video slots often have many lines of winning sequences. Line 1 to 3 are the lines of the three rows. Line 4 might be a diagonal sequence including reel 1 row 1, reel 2 row 2, reel 3 row 3, reel 4 row 2, and reel 5 row 1. There are 243 possible lines, but it is rare for more than 25 lines to be available. You can select 1 line, 25 lines, or any number in between. Each line represents a separate bet, so a 25-line bet is 25x larger than a 1-line bet.Video slots may offer free spins and/or bonus rounds. Free spins are usually triggered by 3 or more scatter symbols. These scatters do not need to be on a winning line. They can be anywhere on the reels. If you get the scatters, the reels will spin on their own for a specified number of spins, usually 10-30. Wins may be doubled or tripled during the free spins, so much of the slots overall payout may be in the free spins. Bonus rounds triggers vary. Like 3-reel slots, bonus rounds involve separate screen where you have the chance of a large win.Fruit Machines -- Fruit machines refers to a type of European (often UK) 3-reel slots. The games usually have a variety of features, such as trails and nudges. Unlike other types of slots, there may be some strategy involved. Outcomes of fruit machines often have some non-random elements. True fruit machines are not common online, although Microgaming offers some AWP games.StrategyMost slots do not have strategy-related decisions. Simply spin and see if you have won or not. One aspect if slot play that is under your control is variance. Using two-tier betting and starting with high variance bets can dramatcially increase return when playing with pre-wager bonuses. Two-tier betting makes most pre-wager slot bonuses EV+ and greatly increases the number of worthwhile bonuses.