VAR, or Video Assistant Referee, consists of a three person team, who take multiple look at contentious or debatable decisions made by the referee on the field. The three person team consists of a current or former referee, his/her assistant and a technician who help the former look at different angles.
Four types of decisions can be reviewed using VAR. Goals (Incidents including, but not exlusive to, offside to fouls during the build up to accidental or intentional hand ball), Penalty decisions, Red Cards and Mistaken identity while producing a card.
The process of reviewing a decision takes place in two ways. The referee can request for a review after a decision is made by him or his linesmen and the VAR team can recommend a review. If the VAR reviews can point to a clear error made, then they can inform the referee and recommend him to overturn the decision.
VAR has not been written into the laws of the game, unlike goal-line technology, which was written into the law in 2012. VAR is being used on an experimental basis in various leagues across the world, with the Major League Soccer (MLS), Hyundai A-league, German Leagues, Italian Leagues and Portuguese Leagues using VAR.
International tournaments like the FIFA Under-20 World Cup, FIFA Confederations Cup and the plan is to use it in the 2018 FIFA World Cup. VAR was recently trialled in the FA Cup as well as high-profile match like the CHelsea vs Arsenal Semi-finals of the Carabao Cup. Kelechi Iheanacho became the first player in England to score a goal assisted by the VAR.
Howard Webb, a former Champions League finals and FIFA World Cup finals referee has said this about the VAR system to ESPN:
"We've been satisfied with the way it's gone. We always knew that it was a big undertaking for any competition that decides to implement VAR.
"It's a big thing to implement, and a lot of work goes into both training our people and preparing our stadiums. Me personally, I've been really impressed by the way that's been put together by MLS."