A slit or other narrow opening, especially one for receiving something. The slot on the side of a door or window allows air to circulate.

The slot in a rotary-indexing filing cabinet has room for several files, allowing them to be inserted and removed quickly and easily. A slot is also a position or place in a sequence, series, or pattern. A slot on a calendar is an open time for scheduling meetings or other events. The term is often used in sports to refer to the area in front of and between the face-off circles on an ice hockey rink, where speed players can gain advantages by moving through it unimpeded.

In modern slot machines, a microprocessor determines how many times each symbol must appear to win. When a new symbol appears, it may occupy multiple stops on the reel displayed to the player, but only one symbol will actually be returned, and the winning amount will depend on which symbols are present and how their probability of appearing is weighted.

Despite their reputation as arcade machines only played by old ladies, slots have become the driving force behind casino profits. They now generate more than twice as much revenue as table games like blackjack and roulette. In addition, players can choose from a wide variety of themes and gameplay styles, from classic 3-reel slots to more modern and riskier 5- and 7-reel games. Some even have themes based on popular TV shows and movies.