In tennis, a Challenge is when a player asks for an official review of a line call. It uses electronic ball-tracking technology to check where the ball landed.
Players can challenge if they think a call is wrong. Challenges are limited, usually three per set. They are only available in big tournaments with the right technology.
The Hawk-Eye system shows a video replay of the ball's path. It uses multiple high-speed cameras to track the ball's trajectory and create a 3D representation of its path. Challenges add excitement to matches and help ensure fair play.