Slot is a small space between the face-off circles of an offensive zone. This area is usually taken up by a running back or wide receiver.
Often, slotbacks replace fullbacks and tight ends. They can run quick routes downfield to generate mismatches with linebackers. Some players like Tyreek Hill stretch defenses vertically with pure speed.
Slot receivers can also serve as check downs for quarterbacks. Slots are most commonly used to create multiple ball receiver formations. However, they are also effective as a check down or as a blocker.
Slot receivers can be as many as three on the field at once. The formation can be confusing for defenders. In addition, a single slot receiver can often make plays. Unlike wide receivers, slot receivers are faster and more nimble. A slot receiver can run a slant, a short route, or a quick out.
Slot receivers can line up in either the inside or outside slot. Inside slots line up just behind the offensive line. On the outside, the slot receiver lines up slightly behind the line of scrimmage.
Slot receivers can also block or pick up defensive linemen breaking through the line of scrimmage. They can then run quick outs to the middle of the field.
Defenses with a slot receiver may need to change their formation to protect the quarterback. For example, the nickel cornerback might need to take on the responsibilities of the wide receiver. Other teams may need to add more defensive backs to cover the slot.