A slot is a specific area within a computer or other device where software can store data. The term is also used to refer to the corresponding hardware slot, such as an expansion card or a peripheral component interconnect (PCI) slot.

The slot element is a part of the HTML specification and is used to create placeholders for content. It can be placed inside a div> or span> element and it can be named using the slot> tag with the name attribute.

Whether an old-fashioned One Arm Bandit or a state-of-the-art video slot, the basics are the same: A player inserts cash or, in “ticket-in, ticket-out” machines, a paper ticket with a barcode, then activates the machine by pressing a lever or button (either physical or on a touchscreen). The reels spin and, when they stop, reveal symbols that pay out credits based on the machine’s pay table. Symbols range from classic fruits and bells to stylized lucky sevens. Often, slot games have a theme, and bonus features align with that theme.

As technology evolved, manufacturers added electronic components that allowed them to weight particular symbols. This reduced the number of possible combinations but still limited jackpot size. Then, in 1963, Bally Manufacturing Company introduced the first electromechanical slot with sensors that allowed all three lines to offer payouts and allowed for multiplier machines. By the 1980s, electronic advances made it possible to replace the mechanical wheels with a Random Number Generator, or RNG, which ensures that each spin is random. The RNG is the heart of a modern video slot, and it regulates clever statistical models built into every machine, such as volatility.