Goal Line Technology: How it works?
Goals have always been awarded when they should not have been and disallowed when they should have stood, because referees and linesmen are unsighted or too far from the action.
Probably the most famous cases on the international stage, curiously all involve England, but the three events span 46 years. The argument still rages to this day on whether Geoff Hurst's controversial third goal in the 1966 World Cup final at Wembley, awarded by referee Gottfried Dienst and Soviet linesman Tofik Bakhramov, actually crossed the line.
Then, in the 2010 World Cup against Germany, Frank Lampard had a perfectly good goal wiped out as England slipped to a 4-1 defeat, a decision which led FIFA president Sepp Blatter to apologise and push for goal-line technology to be introduced. And in last year's Euro 2012, Ukraine were on the receiving end when Marko Devic's effort, which had clearly crossed the line, was hooked away to safety by John Terry.
Goal-line Technology (GLT) will be in place for this year's Confederations Cup in Brazil, as a dress rehearsal for next year's World Cup when it will be fully operational.
At present, two rival systems have been licensed by FIFA - although when it comes to putting the contracts out to tender, two more German firms are expected to throw their hats into the ring. The most high profile system is Hawk-Eye.
Hawk-Eye works by utilising six cameras at each goal to track the ball on the pitch, not dissimilar to the system in use at the Wimbledon tennis tournament.
The British system's software employs "triangulation" to pinpoint the exact location of the football and if it crosses the goal-line, then an encrypted radio signal is sent to the referee's wristwatch to indicate a goal has been scored.
In line with FIFA's requirements, the whole process takes less than a second to complete.
The other competing system is GoalRef from Germany. GoalRef uses a microchip implanted in the ball and low magnetic waves around the goal. The system detects any change in the magnetic field on or behind the goal-line to determine if a goal has been scored and, again, the process takes under one second for a message to be relayed to the referee.
Barring any last-minute problems, the expectation is that one or both systems will be used for the Confederations Cup and the World Cup. And in line with England's history of controversy with goal-line incidents, London bookmakers have immediately quoted England at 66-1 to have a goal awarded by goal line technology at the 2014 World Cup.
The same odds are quoted for a disallowed goal. Or anyone who fancies a more ambitious flutter should get down to Ladbrokes and put money on England at 400-1 to become the first side to win a major tournament thanks to being awarded a goal in the final under the new rules.
Two systems, Hawkeye and Goalref, have so far been licensed by FIFA and both were used at last year's World Club Cup in Japan, one in each of the two stadiums, where goal-line technology was employed for the first time.
FIFA said a third system, developed in Germany, have already passed examinations and that the providers were in licensing discussions. A fourth system, also German, has also been tested.
FIFA confirmed goal-line technology was "successful" at the World Club Cup, although there were no incidents where it had to be used. It intends to install goal-line technology at all 12 venues at the 2014 World Cup in Brazil.
"After a successful implementation of goal-line technology (GLT) at the Club World Cup in Japan in December 2012, FIFA has decided to use GLT at the Confederations Cup Brazil 2013 and 2014 World Cup," FIFA said in a statement.
"The aim is to use GLT in order to support the match officials and to install a system in all stadia, pending the successful installation, and pre-match referee tests. FIFA said Hawkeye and Goalref would have to join the selection process.
Goal-line technology providers had been invited to join an inspection visit to the six Confederations Cup venues in March. Those venues will all be staging matches at the following year's World Cup.
The use of goal-line technology, to help match officials in cases where it is not immediately clear if the ball has entered the goal, was approved by soccer's rule-making body, the International Football Association Board (IFAB), last year.
The use of goal-line technology had previously been rejected by FIFA, which performed a U-turn following the controversy over Frank Lampard's disallowed goal for England in the 2010 World Cup match against Germany.
However, goal-line technology is not favoured by European soccer's governing body UEFA, which instead prefers to employ two extra linesmen, one on each goal line.
Many critics think that football should go further and allow the use of video replays to help referees make decisions concerning offside, handball and fouls.
Referees have to make split second judgments with the naked eye while millions of television viewers are treated to slow-motion replays, from different angles, which often show clearly whether the official was right or wrong.