Instant replay in major sports:
NCAA football: Replay officials in the press box can review all plays and make final decisions. Coaches have a limited number of challenges.
NBA: Officiating crew can use courtside monitors in limited situations, including last-second and three-point shots.
Major League Baseball: Umpires leave the field to review disputed home runs. Beginning this season, fan interference and trapped balls can be reviewed.
NHL: Goal/no goal calls are reviewed by an on-site video goal judge and by officials in a Toronto "situation room."
Tennis: The Hawk-Eye computerized system is widely used at top-tier events. Players can challenge a limited number of line calls per set.