A post is a moderate to deep passing route in American football in which a receiver runs 10–20 yards from the line of scrimmage straight down the field, then cuts toward the middle of the field (towards the facing goalposts, hence the name) at a 45-degree angle.
The post route is designed to beat the opposing secondary deep down the field, resulting in a long pass completion. It works particularly well against secondaries that don't have more than one safety who is effective in coverage, or against defenses that employ 2 or 4 deep zone players, leaving a void deep down the middle. If the safeties play deep enough to stop it, the post route tends to open space for shorter pass routes over the middle. Also, the threat of a post route can force safeties to play far from the line of scrimmage, reducing the number of defenders available to slow down the running game.
Cover 3 packages can be effective against the post route if the defender in middle deep coverage is perceptive enough. Also, since the post route is one of the longest routes, an effective pass rush can force the quarterback to get rid of the ball before the receiver can get open.
To run the route effectively, a wide receiver must have excellent speed and should be adept at catching the ball in traffic if the safety closes to break up the pass.
A variant of the post pattern, in which the receiver cuts infield at a shallower angle, is called a skinny post. It is designed to find a hole in deep coverage, cutting shallow inside the deep sideline defender, but not far enough to draw the middle defender.