A narrow notch, groove, slit, or opening, especially one for receiving or admitting something, as a coin or a letter. Also: (informal) a position in a group, sequence, or series: The program was slotted into the broadcasting schedule.

Casino managers have long resisted increasing their all-important slot house edge, fearing that players will be able to detect the hidden price increase and go elsewhere to play. But this conventional thinking may be costing them dearly.

The first modern slot machine was invented in 1894 by Charles Fey, a mechanic in San Francisco. He created the Card Bell, which featured three spinning reels with symbols such as horseshoes, poker hands, and the eponymous Liberty Bell. The machine paid out cash if the symbols lined up in a winning combination. Its handle set the reels in motion when pressed, and the machine displayed the total payout on a screen.

By the 1970s, video slots began to replace mechanical machines. These games used internal computer hardware to determine the outcome of each spin, rather than rotating physical reels. They were programmed with a variety of themes and immersive bonus games.

With the advent of microprocessors, game developers have been able to create slots with far more complex features than their mechanical ancestors. Many of these slots feature immersive storylines and complex bonus games that encourage players to stay longer at the machines. However, some people develop gambling addictions and struggle to control their slot play.