In the sport of football, there are different types of receivers on an offensive unit. Some receivers may be lined up in the "slot" area, positioned between the offensive line and another wide receiver. Slot receivers may be specialized for this specific position or just wide receivers who get lined up in the slot.
The slot receiver is usually lined up just behind the line of scrimmage, but may need to be on the line of scrimmage to maintain seven players on the line.
In the past decade or so, the professional game has started to rely on slot receivers a lot more. Physically, slot receivers tend to be shorter and quicker than most traditional wide receivers.
On passing plays, slot receivers run routes that correspond with the other receivers in an attempt to confuse the defense. Slot receivers often face an increased risk of injury, though, because they are closer to the middle of the field and therefore more vulnerable to big hits from different angles.
Slot receivers are also often used in motion before the ball is snapped. Players are set in motion so that the quarterback may be able to read the defense. If a defensive back follows a player in motion across the center of the formation, the defense is likely in man-to-man coverage. But if the defense reacts minimally to the receiver's movement, they are likely in a zone coverage scheme.
Although the slot receiver is a generally new concept, there are some legendary players who thrive when lined up in the slot. These include Charlie Joiner, Brandon Stokely, and Wes Welker.