A net touch occurs when any part of a player's body contacts the net while the ball is in play, and it is called as a fault against the player who touched it, ending the rally in the opposing team's favor. The rule exists mainly to prevent a player from using the net for support while blocking or attacking, which would give an unfair advantage. Incidental contact that has no effect on play — for example, hair or a loose piece of clothing brushing the net without disturbing it — is generally not penalized under modern FIVB rules, which tightened the standard specifically to allow referees to ignore harmless contact.
A foot fault is called on a serve when the server steps on or over the end line — the boundary line at the back of the court — before making contact with the ball. The server may jump from behind the line and land inside the court after contact, which is legal and in fact standard technique for a jump serve, but the foot (or any part of the body) may not touch the line or the court itself at the moment of contact.
Centerline crossing
A related fault involves the centerline beneath the net: a player may not fully cross into the opponent's court under the net, though under current FIVB rules a foot or hand that partially crosses the line is legal as long as some part of it remains on or above the line and the contact does not interfere with an opponent.
How referees judge intent and effect
Modern officiating on both net touches and centerline crossings generally applies an 'effect on play' standard rather than a strict letter-of-the-law reading: an official asks whether the contact actually interfered with the opponent's ability to play the ball, or whether it gained the player some advantage, rather than penalizing every conceivable technical violation regardless of consequence. This is a deliberate, relatively modern shift in officiating philosophy, and it means two visually similar moments — a player's hair grazing the net versus a player pushing off the net with a hand — can be ruled completely differently depending on whether the contact plausibly changed the outcome of the play.
