On June 27, 2010, in the round of 16 of the World Cup in South Africa between England and Germany, Frank Lampard hit a shot from outside the area that hit the crossbar, clearly hit the goal and bounced off. The referee did not grant it. The image of the ball crossing the goal line between 30 and 50 cm, without any human official being able to certify it, traveled on television and forced FIFA to do what it had been avoiding for more than a century, which was to automate the most binary decision in football. Twelve years later, goal-line technology (GLT) detects when the ball crosses the line with an error of less than 1.5 or 2 centimeters (the threshold required in the tests) and communicates the decision to the referee in less than a second. Paradoxically, determining whether there is a goal seems a trivial decision, but from a technological point of view it is one of the most demanding problems in sports refereeing. The ball can exceed 100 km/h, bounce off the crossbar, be hidden by several players and remain just a few tenths of a second close to the line. For a technology to be accepted by FIFA, it is not enough for it to work most of the time, it must do so practically always, in any stadium, under rain, fog, artificial lighting or extreme media pressure. The story of goal-line technology is, to a large extent, the story of how engineering managed to turn an instantaneous decision into a verifiable physical measurement. FIFA and the International Football Association Board (IFAB), the two bodies responsible for changing the laws of the game, resisted introducing technology for several documented reasons: - Universality of the game: any regulatory modification affects both the Champions League and a rural field in any corner of the world. Imposing expensive technology was not compatible with historical doctrine. - Risk of “technification” of football: the belief that refereeing imperfection was part of the culture of the game. - Lack of a robust system: Until the 2000s, no existing technology simultaneously met requirements for centimeter accuracy, sub-second latency, and robustness to moisture, dust, and shock.