In American football, a catch is considered complete when a player secures possession of the ball in his hands or arms; maintains control of the ball long enough to perform an act common to the game (such as advancing the ball, passing it, or attempting to score); and survives the “football move” requirement.
The “best” catches are often those that are made in difficult circumstances, such as when the player is tightly covered by a defender or when the ball is thrown into a crowd of players. These catches often require a great deal of skill and athleticism, and they can be very exciting to watch.