On a passing play the receiver looks to get open on the field for a pass thrown by the quarterback. A completion is a pass that's caught. An incompletion is a pass that is not caught or a throw that goes out of bounds.
A wide receiver is a receiver who stands wide near the sidelines at the start of a down on the scrimmage line. Wide receivers run complex routes on the field to fool defensive players and to create openings on the field to catch passes.
A tight end is a receiver that is more flexible than a wide receiver. Tight ends can be extra blockers or catch passes based on the play design. Tight ends are on the strong side of the football field.