A slot is a narrow opening into which something can be fitted, such as the hole that accepts coins in a slot machine or the time slot on a calendar. A slot can also refer to a position in a queue or schedule. The etymology of slot is unclear; it may be related to the word groove or channel, or perhaps from the verb to slot, meaning to place snugly into a gap. For example, a car seat belt slots easily into the slot in which it fits.
Modern slot machines look like the old mechanical models, but they operate on a different principle. The reels have pictures on them, and winning or losing is determined by which symbols line up with the pay line, a line running vertically through the middle of the machine’s window. The payout is determined by how many matching symbols land on the pay line and whether they include a wild symbol, which can substitute for other reel symbols.
A machine’s program is carefully designed and tested to achieve a certain payback percentage, which is shown in its pay table. The pay table will display all of the game’s standard symbols alongside their payout values for landing (typically) three, four or five matching symbols on a payline. The pay tables will also include information on any bonus features that the slot has. Often, they will be accompanied by visuals that fit in with the slot’s theme and are easy to read and understand.