<P> In association football, goal - line technology (sometimes referred to as a Goal Decision System) is the use of electronic aid to determine if a goal has been scored or not . In detail, it is a method used to determine when the ball has completely crossed the goal line in between the goal - posts and underneath the crossbar with the assistance of electronic devices and at the same time assisting the referee in awarding a goal or not . The objective of goal - line technology (GLT) is not to replace the role of the officials, but rather to support them in their decision - making . The GLT must provide a clear indication as to whether the ball has fully crossed the line, and this information will serve to assist the referee in making his final decision . </P> <P> Compared to similar technology in other sports, goal - line technology is a relatively recent addition to association football; its integration having been opposed by the sport's authorities . In July 2012, the International Football Association Board (IFAB) officially approved the use of goal line technology, amending the Laws of the Game to permit (but not require) its use . Due to its expense, goal - line technology is only used at the highest levels of the game . Goal - line technology is currently used in the top European domestic leagues, and at major international competitions such as the 2014 Men's and 2015 Women's FIFA World Cups . </P> <P> In association football, a goal is considered to be scored if the whole of the ball crosses the goal line between the goalposts and under the crossbar . In most cases, this is relatively unambiguous (goal nets being a low - tech way of verifying that the ball passed the correct side of the goalposts). Occasionally however situations occur when it is difficult for referees and their assistants to tell if a goal has been scored before a rebound, save, or defender's clearance from the goal area . </P>

When was goal line technology introduced in football