A slot is a narrow notch, groove or opening, such as a keyway in a piece of machinery or a slit for a coin in a vending machine. It can also refer to a position in a series, sequence or carousel.

A modern casino slot machine has a credit meter that displays the number of credits or total value on the machine. Often the meter is located on the front of the machine, next to the spin button. On mechanical machines, the meter is a seven-segment display; on video slots, it may have stylized text.

Traditionally, mechanical slot machines and pub fruit machines (also known as pulltabs) only offered one payline, which meant that any winning combination could only be made from the symbols displayed on that one line. However, with the advent of microprocessors in slot machines, manufacturers began to allow for more than one payline per reel, resulting in greater combinations and larger jackpot sizes.

Many modern slots have multiple paylines, and you can usually see the number of active paylines in the pay table. The paytable will also show what each symbol is worth — the higher the value, the more you can win if you hit three or more of them.

Depending on the game, there may be additional features like scatters or bonus symbols, as well as wilds and other special symbols. If the slot has a progressive jackpot, details of how to win this will be included in the paytable.