What do you understand by Umpire Decision Review System in Cricket? Discuss its various components. Explain how silicone tape on the edge of a bat may fool the system. (UPSC 2013)

Umpire Decision Review System (DRS) is technology-assisted review in cricket that lets players challenge on-field decisions to improve fairness in close calls.

• Ball tracking: Hawk-Eye traces the ball and predicts its path, mainly for LBW decisions.
• UltraEdge/Real-time Snicko: Microphones and sound analysis detect faint bat-ball contact.
• Hot Spot: Infrared cameras show heat marks at the point of contact.
• Video replay: Slow-motion cameras help third umpires check run-outs, stumpings, catches and boundaries.

Silicone tape on a bat edge can fool Hot Spot by reducing friction and absorbing heat, so a thin nick may not leave a clear thermal mark, though sound-based tools like UltraEdge may still detect it. Thus, DRS combines multiple systems to reduce error, since no single method is foolproof.