The wide receiver is the player who specializes in catching passes and running complex routes on the field. He is usually positioned out wide toward the sidelines, hence his name, and makes sharp cuts to evade defenders and run down an open lane for a pass. Oftentimes, wide receivers get put in touchdown scoring situations.
Once the football is thrown, the wide receiver must try to catch the ball before his opponent stops him. If the wide receiver misses the ball and it hits the ground, this is called an incomplete pass or incompletion. An incomplete pass is any unsuccessful pass that is not caught by an eligible receiver. So If the wide receiver misses the catch and the ball hits the ground, that means the official will call the pass as incomplete.
Incomplete passes can take many forms:
Unless the play was 4th down, the football would go back to the same spot (line of scrimmage) to start the next down if there is an incomplete pass. If it was 4th down, the possession of the ball would go to the other team for a turnover on downs. Missing a catch can be very discouraging, especially if it's on a 4th down.
If you want to learn more about the wide receivers and their roles in football, check out the following resources: