A slot is a narrow opening in a machine or container. He dropped a coin into the slot and dialed. In football, a slot receiver is a second wide receiver that lines up inside the left or right tackle. They are not as fast as the other wideouts but are much more versatile and can run routes up, in and out and even back. This is what makes them very useful in the modern game of football as the offenses become more spread out.
They also block for the running backs on outside run plays. They pick up blitzes from linebackers or secondary players and give the RB more space to cut or run the route. On passing plays, they can run a variety of routes and are most effective when they have good chemistry with the quarterback.
Depending on the game, slot is either high or low volatility. High volatility slots do not pay out often but when they do it is usually big. Low volatile slots, on the other hand, payout often but not large amounts.
Slots are dynamic placeholders that can be filled with content dictated by a scenario using the Add Items to Slot action or by a targeter that uses the Slots property. To read more about slots and scenarios, see the Using Slots chapter in the ATG Personalization Programming Guide.