Throw-inWhen the ball has crossed the touchline; awarded to opposing team to that which last touched the ball.
The throw-in is taken from the point where the ball crossed the touch-line (side lines). The throw-in is taken by the opponents of the player who last touched the ball when it crossed the touch-line, either on the ground or in the air. Opposing players may stand at any distance from the thrower but no closer than 2m (2yds), so long as they are still on the pitch. A player may take a throw in at a distance further back from the touch-line, and, typically, a referee will tolerate small discrepancies between the position where the ball crossed the touch-line and the position of the throw in.
At the moment of delivering the ball, the thrower must face the field of play, have both feet on the ground on or outside the touch line, and use both hands to deliver the ball from behind and over their head.
The ball becomes in play as soon as it enters the field of play.
A goal may not be scored directly from a throw-in, although if any player makes slight contact with the ball before it enters the goal, the resulting goal may be credited to the thrower. If a player throws the ball directly into his opponents goal without any other player touching it the result is a goal kick to the defending side.
Similarly an own goal (when a team scores a goal on themselves) cannot be scored directly from a throw-in – if a player throws the ball directly into his own goal without any other player touching it the result is a corner kick to the opposing side.
The handspring throw-in is a dramatic type of throw-in, rarely used in competitive games, where the player completes a front handspring (somersault) while holding the ball. Instead of landing on the hands during the handspring, the player’s weight is momentarily supported entirely by the ball. This type of throw-in follows all of the rules that require the player to have both feet on the ground when he/she is releasing the ball, the ball is thrown from behind the head, and the ball is thrown with equal force by both hands. Strong abdominal muscles are required for this throw-in. 
It was Steve Watson of Newcastle United was famed for this technique and was able to throw the ball over 30 m. Brazilian Leah Lynn Gabriela Fortune has also been reported to be able to throw over 30 yards (27 m) with the technique. 
If an opposing player fails to respect the required distance before the ball is in play or otherwise unfairly distracts or impedes the thrower he or she may receive a caution (yellow card).
If the thrower fails to deliver the ball as per the required procedure, or delivers it from a point other than where the ball left the field of play, the throw-in is awarded to the opposing team.
It is an offense for the thrower to touch the ball a second time until it has been touched by another player; this is punishable by an indirect free kick to the defending team from where the offense occurred, unless the second touch was also a more serious handling offense, in which case it is punishable by a direct free kick or penalty kick, as appropriate.
The optimal release angle for attaining maximum distance is about 30 degrees, according to researchers at Brunel University. This angle balances the objectives of maximizing height, which allows the ball more time to travel horizontally, while minimizing air resistance, which slows the ball thus reducing its horizontal distance.
Delivering the ball into the penalty area from a long distance with a throw-in can be a great attacking skill, similar to a corner kick or an indirect free kick. This is a difficult distance to reach with a throw-in, and the ability to do so is a valuable skill. An early exponent of the skill was Bill Shankly when playing for Carlisle United and Preston North End in the 1930s. Shankly’s dedication was such that he used to practice long throws during his summer breaks when he returned to his home village. He would throw balls over a row of houses and get the small boys of the village to fetch them back for him.
Rory Delap, a midfielder for Stoke City is known for his long-throw abilities having resulted in many goals for Stoke. In fact, the danger factor of Delap’s long throw-ins for Stoke have resulted in opponents preferring to put the ball out for a corner rather than for a throw-in.