A slot is a position in a queue, schedule or calendar. Often used in reference to a specific time, it may also refer to a place for an event or activity. A slot can be booked by anyone who is authorised to do so. The band was able to slot in some extra rehearsals before the show. He was able to fit into the slot at the top of the program.

In computer science, a slot is an element of a data structure that holds the data of an object. A variable can be assigned to one of several slots and stored in memory. The value of a slot can be changed at any time and the object will still hold the data that it was stored in its previous slot. This allows the object to be easily reconstructed from its data, even if the original data is deleted or overwritten.

The first slot machine was created by Sittman and Pitt in 1891. It was a mechanical contraption with five reels and 50 poker cards, where winning was achieved by lining up matching poker hands. The machine was later improved upon by Charles Augustus Fey, who added a lever and fruit symbols to the mix. The sixties saw the arrival of the first electromechanical slot machines, whose payouts were much larger than those of their mechanical predecessors.

When playing a slot machine, players can choose between fixed and variable paylines. The latter offer a greater number of opportunities to win, but can also require a higher stake. A percentage of the total amount wagered is returned to the player over time, and this is known as the return-to-player (RTP) rate.

A slot is also a narrow notch, groove or opening, such as a keyway in a piece of machinery or a slit for coins in a vending machine. Alternatively, the term can be used to describe a position in a sequence or series, such as the number of seats in a bus or the amount of space left for passengers on an airplane.

Lastly, the word can be used to describe an allocated time and place for aircraft takeoff or landing, as authorized by an airport or air-traffic management authority: The new airline has 40 more slots at U.S. airports.

Psychologists have studied the connection between slot machines and gambling addiction, finding that people who play these games reach a debilitating level of involvement with gambling three times faster than those who engage in other forms of gambling. The results of the study have led to increased scrutiny and regulation of these machines, as well as warnings to gamblers that slot games are especially addictive. Two cases in Colorado in 2010 where software errors resulted in indicated jackpots of $11 million and $42 million have highlighted the issue. Psychologists have also found that video slot players are more likely to engage in risk-taking behaviours, including chasing losses and spending money on reload bonuses.