Under what circumstance must a referee stop play?

A referee is required to stop play primarily to ensure the safety of the players on the field. When there is a serious injury, the referee needs to halt the game to allow medical personnel to attend to the injured player without the risk of further injury. This priority on player safety is a fundamental aspect of officiating in soccer and is in line with the rules set forth by the governing bodies of the sport.

While there are other situations like fouls, the ball going out of bounds, or goals being scored that also result in the stoppage of play, they do not carry the same urgent need to address player safety. For instance, while a foul may warrant a stoppage for a free kick or other disciplinary measures, it does not necessitate medical attention. Likewise, the ball going out of bounds or a goal being scored are routine aspects of the game, and the play naturally resumes without immediate concern for player health. Thus, the circumstance that requires the referee to stop play is specifically tied to serious injuries.