Explained: The controversial Umpire’s call in DRS
According to the International Cricket Council (ICC), the DRS is a technology-based process for assisting the match officials with their decision-making. On-field umpires may consult with the third umpire (an Umpire Review) and players may request that the third umpire take another look at a decision made by the on-field umpires (a Player Review).
Source: Cricket News: Latest Cricket News, Live Scores, Results, Upcoming match Schedules | Times of India