VAR definition in football is video assistant refree.Usually,the video assistant refree is selected in those who has got the certification of professional football refree.The role of the video assistant referee is to provide information to the referee through the replay of video, to assist the referee in correcting clear and obvious errors and omissions that change the course of the game, and to improve the accuracy of decisions..However,there is a unwritten rules that he video assistant refree should not do any decision by itself but to help refree to make a decision in a correctly way.
According to the explicit rules made by FIFA, VAR can only intervene in four situations involving a ball in the goal, a red card, a red or yellow card for the wrong person and a penalty kick. In all other cases, VAR cannot intervene even if the referee has made a misjudgement. When there is a situation on the field that requires VAR intervention, the video assistant referee will capture every moment of the field of play from multiple angles with multiple cameras spread throughout the field of play and adjust the video to the appropriate point in time to assist the referee in making the correct decision based on the information provided by the video.
The first time VAR was used in an official match was on 15 December 2016 in the 3-0 Club World Cup semi-final victory of Kashima Antlers over Colombian side Atletico Nacional, when the referee decided to award a penalty based on a VAR prompt. VAR was then used for the first time at the 2018 FIFA World Cup in Russia, the most important tournament under the FIFA umbrella. To ensure the smooth running of the job, the video referee team usually consists of one video assistant referee and three assistants. In addition, the video replay room is also staffed by four specialised personnel in accordance with the regulations to assist in the replay of the footage, and a FIFA-appointed official supervises the work of the video assistant referee team.