A slot (plural slots) is a hole or opening in something, especially a piece of machinery. In aviation, a slot is an opening in the wings or tail of an airplane used for aerodynamic purposes (such as providing lift) and can also be a structural component in aircraft fuselages.

While casino games like blackjack and roulette may conjure images of high-stakes bouts of chance where fortunes can be won or lost in seconds, Schull says slot machines are now the driving force behind gambling profits, bringing in as much as 85 percent of industry revenue. She points to a subtle advance that has helped revolutionize slot machine play: The computerization of slot machines allowed casinos to control things such as the percentage payback and odds.

Another important change came when casinos switched from requiring players to feed coins into the machines to accepting bills or player cards with magnetic strips that can be scanned to withdraw credits from the machine. This meant that players could stay in the zone longer without thinking about how much they were spending.

In order to keep the game simple and leave room for improvement, this tutorial focuses on the basic features of a slot machine: the slot symbol and the total number of credits available to be played. A bar at the top of the game window holds these elements and buttons to start and adjust the amount of credits to be played. In addition, the player can also choose to play on all or just some of the nine winning lines.