A slot is a narrow opening, especially one for receiving something, such as a coin or letter. It is also a term used to describe the space in a computer motherboard where an expansion card fits, such as an ISA, PCI, or AGP slot.
A more recent use of the word is in reference to airport slots, which are authorizations to take off or land at an airport during a specific time period. Airlines must compete to hold slots, and they can be sold for substantial amounts of money. Slots are important at highly congested airports, such as Heathrow in London, and they can reduce delays caused by too many flights trying to take off or land simultaneously.
In the NFL, a slot receiver is a small, fast player who can stretch the defense vertically through slant routes and quick outs. They are much more effective than traditional wide receivers, who run longer routes that require them to beat coverage and make physical contact with defenders. A slot corner can also help prevent big plays, and they are a critical component of teams that want to win Super Bowls.