Javelin: the sport

The javelin throw is a track and field athletics throwing event where the object to be thrown is the javelin, a spear approximately 2.5 meters in length.
Unlike the other throwing events (shotput, discus, and hammer), the technique used to throw the javelin is dictated by IAAF rules and "non-orthodox" techniques are not permitted. The javelin must be held at its grip and thrown overhand, over the athlete's shoulder or upper arm. Further, the athlete is prohibited from turning completely around such that his back faces the direction of throw. In practice, this prevents athletes from attempting to spin and hurl the javelin sidearm in the style of a discus throw. Instead of being confined to a circle, javelin throwers are provided with a runway 4 meters wide and at least 30 meters in length, ending in a curved arc from which their throw will be measured; athletes typically use this distance to gain momentum in a "run-up" to their throw. Like the other throwing events, the competitor may not leave the throwing area (the runway) until after the implement lands. The need to come to a stop behind the throwing arc limits both how close the athlete can come to the line before the release as well as the maximum speed achieved at the time of release.
The javelin is thrown towards a "sector" covering an angle of 29 degrees extending outwards from the arc at the end of the runway. A throw is legal only if the tip of the javelin lands within this sector, and the tip strikes the ground before any other part of the javelin. The distance of the throw is measured from the throwing arc to the point where the tip of the javelin landed, rounded down to the nearest centimeter.
Competition rules are similar to other throwing events: a round consists of one attempt by each competitor in turn, and competitions typically consist of three to six rounds. The competitor with the longest single legal throw (over all rounds) is the winner; in the case of a tie the competitors' second-longest throws are also considered. Competitions involving large numbers of athletes sometimes use a "cut": all competitors compete in the first three rounds, but only athletes who are currently among the top eight or have achieved some minimum distance are permitted to attempt to improve on their distance in additional rounds (typically three).