A thin opening, groove, or hole, especially one for receiving something, as a coin or letter. Also: a position or time, as in an appointment, a seat on a plane, or a spot at the front of a line.
In computer science, a slot (plural: slots) is an empty or unoccupied region on a device, circuit board, or expansion card that can be used to hold a piece of hardware with a specific capability. For example, a motherboard may have several slots for adding ISA or PCI cards that provide additional functions such as video acceleration or disk drive control.
On running plays, the slot receiver is often responsible for blocking defensive backs and outside linebackers. In addition, he will sometimes run his route close to the middle of the field. This is to put as much distance between him and the defense as possible before the snap.
The slot receiver must be quick, as all wide receivers are. However, speed and agility are emphasized more for this position because the slot receiver must be able to both catch passes and block defenders. Additionally, he must be able to execute a variety of routes and run complex patterns that require a high degree of elusion and evasion. On passing plays, the slot receiver must also coordinate with other receivers in order to confuse the defense and maximize the effectiveness of each reception. Lastly, the slot receiver must be able to block effectively — even against larger safeties and linebackers.