A narrow depression, groove, notch, or opening, especially one for receiving something, such as a coin or a piece of paper. Also: (in slang) an allocated position in a schedule or sequence: I’ve slotted you in for 2 p.m.

In a slot machine, players insert cash or, in “ticket-in, ticket-out” machines, paper tickets with barcodes, into a designated slot. The machine then activates a series of reels marked into horizontal segments by varying symbols and pays off credits based on the combinations that appear when the reels come to rest. The symbols vary according to the machine, but classics include bells, stylized lucky sevens, and fruit. Most slot games have a theme, and the symbols and bonus features align with that theme.

The development of digital technology has changed the way slots are operated. Although some modern slot machines still incorporate a lever as a skeuomorphic design element, most are operated using buttons or touchscreens. The microprocessors inside these machines assign a different probability to each symbol on every reel, so that a given combination may appear very often to the player, even though the probabilities of other payouts are much lower. This allows for a greater variety of bonus features, as well as more detailed pay tables that list the odds of various symbols appearing on a winning combination. This information is typically displayed above or below the area containing the reels, and in some cases within a help menu.