What is the role of a third umpire?

What is the role of a third umpire?

In international cricket matches, the third umpire (or TV Umpire) is an off-field umpire who makes the final decision in questions referred to him by the two on-field umpires. Television replays are available to the third umpire to assist him in coming to a decision. An on-field umpire can, at his own direction use a radio link to refer any close decision to the third umpire.