What Is a Slot?


A slot is a narrow opening, usually in the form of a track or a plate, into which something may be inserted. It is also the name of a device used to hold removable memory cards, such as those used in some modern digital cameras.

A slot in a computer circuit is a location where data or instructions can be stored temporarily. The word is also used to describe a reserved portion of memory, often for use with an operating system kernel, that can be accessed by the kernel and by applications programs. It is not to be confused with a disk drive “slot” (which holds a physical disk in a stationary housing), although the two are sometimes confused in casual use.

The term is also used to refer to a computer hardware interface, such as an ISA, PCI or AGP slot. It may also mean an expansion bus slot, an expansion card slot or a position on a motherboard that accepts memory chips. A slot is a very common component of a personal computer, so much so that it has spawned an entire industry, with companies offering products like PCI and AGP expansion slots and motherboards that have built-in AGP and ISA slots.

Most modern slot games are computerized, with reels becoming a thing of the past. Nonetheless, they still work roughly the same way: The player inserts cash or, in ticket-in, ticket-out machines, a paper ticket with a barcode into a designated slot and activates the machine by pressing a button or pulling a handle. The machine then spins the reels and displays symbols. Which ones land on the pay line, a line running horizontally across the center of the machine’s viewing window, decide whether the player wins or loses.

When a slot machine is turned on, its random-number generator assigns a number to each possible combination of stops on the reels. When a signal is received, from anything as simple as the button being pressed to the handle being pulled, the random-number generator selects one of those numbers and the reels stop on that position. Between signals, the random-number generator continues to run, producing dozens of combinations each second.

When people play a slot, they often believe that the machine they’re playing is “due to hit.” While it’s true that some machines are hotter than others, it’s also true that no machine is ever due to hit. This belief is likely based on the fact that casino owners place machines at the ends of aisles because they want other customers to see them winning, and that casinos program their machines to return a certain percentage of money over time. However, this theory is flawed in several ways.