A slot machine is a mechanical device employing three, four, five or more circular reels of varying dimensions. Each of these reels has several symbols either painted on or attached to it. These symbols can be anything at all, although the most common designs are cherries, bars, and - the jackpot symbol - the number 7. Whatever the symbol on the machine, it makes absolutely no difference to how the machine will play or what and how much it will pay out. All these details are determined by the computer program carried by a tiny chip inside the machine's electronic brain. You could put pictures of your kids, rocks, spaghetti, cheese, or anything there, and, if they lined up on the pay liner you'd win the top jackpot.  In case you have never played a slot machine, or have not played some of the newer slot machines lately, I shall begin by describing how you start.

Players begin play by inserting a specified number of coins, or gaming tokens, into a coin receptacle slot provided on the front of the machine, and then pulling the handle affixed to the right side of the machine which sets the reels spinning, The reels come to a stop in order left-to-right on the display screen. The object is to line up matching symbols [matching winning combinations] on the pay line, usually a center stripe painted across the viewing screen. The schedule of winning combinations is usually displayed on the front or just above the machine, indicating the hierarchy of winning combinations and the amounts that each one pays whenever it appears on the active payline.

Instead of a handle, some modern machines employ a button marked "spin" which you press to start the reels turning, and, like the handler pressing it will spin the reels after the coin, or coins, are inserted. Most modern Slot Machines, like the Video Poker machines, also have a button marked "credit".  If the player presses this button prior to inserting coins, instead of paying winners off in coins, the machine will automatically credit any winnings to a credit meter. The credited winnings appear numerically on the machine's credit meter display, and, as an option, the player then has a choice of playing these credits, or cashing them out. To play the credits, the player can press a button marked "play one credit", and for each time this button is pressed the machine will deduct one credit from the credit meter and register one corresponding coin as "coin in". The player may press this "play one credit" button up to the machine's maximum coin limit.

If, for instance, the machine you are playing takes three coins as maximum, you can press this "play one coin" button three times. These coins are then deducted from the player's credit meter, and credited to the player's next pull. When this is done, the machine will usually say "coin accepted" on the display, or, in some cases, the pay-lines on the machine's display will light up. The effect is the same as if you had put three coins in the slot instead of using the credits you had accumulated. Most of the modern machines also have another button called "play maximum coins", sometime also identified as "play three coins" if that machine's maximum is three coins, or "play five coins" if that machine's maximum is five, and so on. By pressing this button, the player will automatically play the maximum coins which that machine takes.  The player may also cash out these credits by pressing a button marked "collect". By pressing this button, the machine will pay out in coins, or gaming tokens, all the credits indicated on the credit meter. These coins then drop to the tray mounted at the bottom of the machine.