In Football, a route, or sometimes called a passing pattern, is a predetermined path that a receiver takes when running downfield. A route is often designed to be able to maneuver through certain defensive alignments so that the receiver will become open to receive a pass. There are many possible routes that a receiver can take, including an in route, an out route, a fly route, and a curl route. All of the possible routes on a certain play can be laid out into what is called a route tree.
A fly route is a straight path that is run by a wide receiver. It's a path that leads straight to the endzone. A curl route is a deviation of the fly route, where a receiver runs in a straight path, and then at the last second, stops and turns around to make a pass.
The in route and out route are the paths that a player can also run. The in route is when a player makes a sharp turn in toward the center of the field, and an out route is when a player makes a sharp turn to the sidelines of the field.
A receiver and quarterback coordinate on which route the receiver will be running so the quarterback can throw the ball in time of the receivers cut, which is when the receiver makes a hard move to shake off a defender. A receiver can break off from their route if they reach the end of their route and the play is still going.