Slot is a term used for a narrow opening. A slot is often taken up by a wide receiver, but can be taken up by a running back, too.
Slot is also a term for a place in a machine or rink. It can be the keyway into machinery, or it can be a small hole for coins to be placed into.
Slot is also a term for an area in the offensive zone, between face-off circles. The name slot comes from a Middle Low German word, which means a groove.
In soccer, a slot receiver is a player who is allowed to line up on either side of the offense. They can run quick outs or slants, but can also be used to block defenders, protect the quarterback, and catch passes. This is especially helpful in the catch and run game.
Slot receivers may be mixed between both sides of the field, so that they create mismatches downfield. This helps them prevent the quarterback from being sacked. However, it can be difficult to cover a formation with more than three receivers on the field at one time.
Slot receivers are a common feature in NFL games. In some cases, they are used in place of a fullback. For example, Tyreek Hill is known for his ability to stretch the defense vertically, using pure speed.
In other cases, a slot receiver may be used as a check-down for the quarterback. If a defensive lineman breaks through the line of scrimmage, the slot receiver can pick him up.