A slot is a position in a group, series, sequence, or set. It can also refer to a position in a game, such as a winning symbol or reel that pays out. In computer technology, a slot can be used to describe the physical locations of expansion slots, such as an ISA (Industry Standard Architecture), PCI (peripheral component interconnect), or AGP (accelerated graphics port) slot. It can also refer to a memory slot, which is the location in a motherboard where RAM (random access memory) is installed.

In casinos, a slot is the name for a mechanical or electrical device that accepts cash or, in ticket-in, ticket-out machines, paper tickets with barcodes. The machine then activates reels that contain symbols, which can be lined up to form a payline and earn the player credits based on the machine’s paytable. Some slot machines have stacked symbols, which allow a single normal symbol to take up more than one space on the reels, resulting in increased chances of matching multiple symbols and earning impressive amounts of money.

There are many different types of slot, including periodic, expression, and scalar slots. A periodic slot holds data that repeats over a specified time period. For example, a periodic slot could hold a set of monthly evaporation coefficients for a reservoir. When a periodic slot is selected, the Slot Viewer displays a special ornamentation in its column heading indicating that there is an expression to edit or data to view. The slot can be opened in its own Slot Dialog, which can be detached from the viewer by dragging it off, as described in Slot Viewer Functionality.