A slot is a narrow opening or groove. In electrical engineering, a slot is an area in a stator or rotor through which windings can be inserted or removed. A slot can also refer to a position or a period of time within a schedule or sequence. The word derives from English via French esclot and Old Norse slod.

In casino operations, a slot is a compartment in which coins are deposited and collected for payment to players. Typically, slots have a high degree of automation, and the coins are fed into and out of the machine through specially designed coin chutes. In some jurisdictions, slot machines are regulated by state gaming control boards. Some states, such as Alaska, Arizona, and Arkansas, allow private ownership of slots; others, including Connecticut, Hawaii, Nebraska, Tennessee, and South Carolina, prohibit it.

Some slot games have a variety of pay lines and betting options, while others have fixed payout values that are multiplied by the number of coins a player bets per spin. These are often referred to as low-variance slots and are great for building bankrolls without burning them up too quickly. Others focus on big payouts and feature bonus rounds with multipliers and free spins. These are called high-variance slots and can be more exciting, but have larger gaps between wins.

Psychologists have found that people who play video slot machines reach debilitating levels of gambling addiction three times faster than those who play other casino games. They are also more likely to experience gambling depression than those who do not play.