A slot is a dynamic placeholder that either waits for content to be added (passive slot) or is called by a scenario and told to add some content (active slot). Slot properties are used in conjunction with scenarios to define what kind of content will be delivered to a page.

Historically, all slot machines used mechanical reels to display and determine results. The earliest three-reel machines had only 10 symbols per reel, giving them only 103 possible combinations, which greatly limited jackpot sizes. Later, manufacturers introduced electronics that allowed each symbol to occupy multiple stops on the reel and thereby increase the odds of appearing on a payline.

In modern digital slot machines, the process is much faster and more accurate thanks to the use of computer chips. In addition, touch-screen technology is now available as an interaction method. This allows players to interact with the machine in a different way, and opens up new opportunities for bonus games and other features.

In football, a slot receiver is a player who can stretch the defense horizontally by running short routes such as slants and quick outs. These types of players are becoming more prevalent in the NFL as teams look to capitalize on their speed. They are also more effective than traditional boundary receivers who only have the ability to go downfield and inward.