Under normal circumstances, a held ball or lift is one that remains in a player's hands for more than a moment or that is hit with an open-hand underhand. Unlike a ball that is struck out of bounds or a player illegally contacting the net, the held ball infraction is a judgment call by the referee. USA Volleyball rules 9.2.2 states simply that "The ball must be hit, not caught and/or thrown."
The only times that a ball may be "held" for more than a moment in indoor play are when two opponents make simultaneous contact with the ball over the net and on the first play of a team on receiving the ball. In the first circumstance, one player from each team contacts the ball when part of it is directly above the plane of the net, so the ball is held between their hands. This is allowed, and the ball is in play as soon as it releases to one side of the court. In the second situation, if a player makes contact with the ball on his team's first hit, it is legal for the ball to strike him simultaneously in more than one spot, which means the ball could appear to be held for a moment. The contact must be deemed by the referee as to be occurring during a "single action."
Beach rules include those regarding lifts in indoor play, but also take into account the nature of the game: that two players are covering an entire half of the court. In this regard, rule 13.4.2/13.4.3 states that "Plays involving finger action require special attention. If the play is ruled defensive and reactive in nature, as in the case of a hard-driven ball, momentarily held or double-contacted balls are not considered faults." Such contact also is illegal if it follows a block, as long as the ball is still deemed a hard-driven attack--in other words, the block was not significant enough to slow it down much.