(CNN) —
It’s being talked about around the world, dominating discussion in stadiums, crowded pubs and millions of households.
But the talk of the Russia 2018 World Cup so far hasn’t been a wonder goal, horrifying injury or moment of magic.
Instead the three letters on everybody’s lips from Moscow to Melbourne are VAR: the Video Assistant Referee being deployed throughout the tournament.
Laurence Griffiths/Getty Images Europe/Getty Images
The video assistant referee control room in Moscow.
While fans of tennis and rugby will be familiar with technology affecting the game – those sports deploying Hawkeye and the Television Match Official (TMO) respectively – this is the first time in history that football has featured VAR at a World Cup.
And it’s already proving controversial. Here’s everything you need to know. It’s a little complicated but there’s method in the madness.
Regardless of where the match is being played, the VAR team is located in a centralized operation room in Moscow.
That team – made up of one lead video official and three assistants – has access to all 33 of the broadcast cameras inside the stadium, of which 12 are slow-motion.
They also have two additional cameras dedicated to monitoring possible offsides, featuring computer-generated lines projected onto the field of play. For the knockout phase, an additional ultra slow-motion camera will be installed behind each goal.
02:37 - Source: CNN
Former Premier League ref on VAR technology
The VAR team don’t only review footage on the instruction of the referee. They’re constantly checking for “clear and obvious” errors behind the scenes.
It’s important to note VAR is only used in what FIFA deems to be “game-changing” incidents. These are goals, penalty decisions, direct red cards and cases of mistaken identity.
Communication between the referee and the officials watching the video footage is two-way. If the VAR believes the referee has made a mistake, they can advise him at any time via the headset.
If the on-field referee is unsure of a particular decision, he can make contact with the VAR.
Many of the venues for Russia 2018 are thousands of miles away from capital, so communication is made through what FIFA calls a “sophisticated fibre-linked radio system.”
Photos: Eleven cities, 12 stadiums
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Alexander Hassenstein/Bongarts/Bongarts/Getty Images
St. Petersburg Stadium, Saint Petersburg —
Designed by late Japanese architect Kisho Kurosawa to look like a spaceship, the brand new St. Petersburg Stadium was built on Krestovsky Island where the 110,000-capacity Kirov Stadium used to stand.
Photos: Eleven cities, 12 stadiums
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OLGA MALTSEVA/AFP/AFP/Getty Images
St. Petersburg Stadium, Saint Petersburg —
Opened in April 2017, the stadium is equipped with a retractable roof and sliding pitch. Inside, the temperature can be regulated to a mild 59 degrees Fahrenheit (15 C) all year round.
Photos: Eleven cities, 12 stadiums
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MLADEN ANTONOV/AFP/AFP/Getty Images
St. Petersburg Stadium World Cup schedule: Group stage, last 16, semifinal, third-place playoff
Legacy: The 67,000-seater will regain its former name -- Krestovsky Stadium -- and be home to 2007-08 UEFA Cup winners Zenit St. Petersburg.
Photos: Eleven cities, 12 stadiums
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KIRILL KUDRYAVTSEV/AFP/AFP/Getty Images
Ekaterinburg Stadium, Yekaterinburg —
Located 1,000 miles east of Moscow on the site of the old Central Stadium -- once a prominent speed skating venue -- the Ekaterinburg Stadium has retained its original Soviet neo-Classical pillars while adding modern refurbishments and temporary stands.
Photos: Eleven cities, 12 stadiums
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FIFA
Ekaterinburg Stadium, Yekaterinburg —
The additional seats, constructed outside of the original stadium, loom dramatically at either end of the pitch in order to fulfill FIFA's minimum World Cup capacity of 35,000. Recent inspection reports have shown the temporary stands "fully comply with all safety and security requirements," according to a FIFA spokesperson.
Photos: Eleven cities, 12 stadiums
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VASILY MAXIMOV/AFP/AFP/Getty Images
Ekaterinburg Stadium World Cup schedule: Group stage
Legacy: FC Ural, one of Russia's oldest clubs newly promoted to the country's top tier, will continue to use the stadium for its home games. After the World Cup, the capacity will be reduced and it will once again be known as Central Stadium.
Photos: Eleven cities, 12 stadiums
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FIFA
Fisht Stadium, Sochi —
The Fisht Stadium held the opening and closing ceremonies of the 2014 Winter Olympics and is already well-equipped for the demands of a major international football tournament.
Photos: Eleven cities, 12 stadiums
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FIFA
Fisht Stadium, Sochi —
Named after Mount Fisht, a peak in the nearby Caucasus mountain range, the arena's roof was designed to resemble a snow-capped summit.
Photos: Eleven cities, 12 stadiums
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FRANCK FIFE/AFP/AFP/Getty Images
Fisht Stadium World Cup schedule: Group stage, last 16, quarterfinals
Legacy: The 47,700-capacity venue will stage training camps and competitive matches for the Russian national team.
Photos: Eleven cities, 12 stadiums
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OLIVIER MORIN/AFP/AFP/Getty Images
Luzhniki Stadium, Moscow —
It was home to the 1980 Summer Olympics, 2008 Champions League final, 2013 Athletics World Championships and no shortage of musical tours, from Michael Jackson to the Rolling Stones...
Photos: Eleven cities, 12 stadiums
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Lars Baron/Getty Images Europe/Getty Images
Luzhniki Stadium, Moscow —
Now the Luzhniki Stadium has been refurbished -- with the athletics track removed and two extra tiers added -- while preserving its historical facade.
Photos: Eleven cities, 12 stadiums
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DMITRY SEREBRYAKOV/AFP/AFP/Getty Images
Luzhniki Stadium World Cup schedule: Group stage, last 16, semifinal, final
Legacy: The 81,006-seater will retain its status as the country's leading football stadium, hosting competitive international matches and friendlies.
Photos: Eleven cities, 12 stadiums
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Handout/Getty Images Europe
Kaliningrad Stadium, Kaliningrad —
Built in the heart of Kaliningrad on Oktyabrsky Island -- a section of land sandwiched between Poland and Lithuania left largely untouched until its selection as a World Cup venue -- the Kaliningrad stadium is loosely based on the design of Bayern Munich's Allianz Arena.
Photos: Eleven cities, 12 stadiums
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FIFA
Kaliningrad Stadium, Kaliningrad —
Kaliningrad Stadium World Cup schedule: Group stage
Legacy: The 35,000-seater stadium will have its capacity reduced by 10,000 and be home to second-tier side FC Baltika Kaliningrad. A new residential development will be built around it featuring parks, quays and embankments alongside the Pregola river.
Photos: Eleven cities, 12 stadiums
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FIFA
Rostov Arena, Rostov-on-Don —
Located about 20 miles from the Sea of Azov in south eastern Russia, the brand new Rostov Arena is 51m tall -- as high as the Niagra Falls.
Photos: Eleven cities, 12 stadiums
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MLADEN ANTONOV/AFP/AFP/Getty Images
Rostov Arena World Cup schedule: Group stage, last 16
Legacy: As one of the first major projects built on the southern bank of the Don River, architects hope the 45,000-seater stadium will attract a flow of people and investment from the north. It will also host Russian Premier League side FC Rostov's home fixtures.
Photos: Eleven cities, 12 stadiums
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Sandra Montanez/Getty Images Europe/Getty Images
Volgograd Arena, Volgograd —
Built at the foot of the towering Mamayev Kurgan World War II memorial "The Motherland Calls" (pictured), the Volgograd Stadium will replace the demolished Central Stadium and feature an open lattice exterior structure.
Photos: Eleven cities, 12 stadiums
PHOTO:
MLADEN ANTONOV/AFP/AFP/Getty Images
Volgograd Arena World Cup schedule: Group stage
Legacy: The 45,000-seater will become the home ground of second-tier side FC Rotor Vologograd.
