What happens when a substitute enters the field without the referee's permission?

When a substitute enters the field without the referee's permission, the correct outcome is that the referee will award an indirect free kick to the opposing team after showing a yellow card to the player who entered without authorization. This action serves both to penalize the misconduct and to ensure that the match is conducted under the rules.

The rules dictate that all substitutions must be officially recognized by the referee before the player can enter the field. This maintains the integrity of the game and ensures that only properly sanctioned changes are made to the teams. The issuance of a yellow card reflects the referee's authority and the necessity of adhering to the game's regulations concerning player management and conduct on the field.

The resulting indirect free kick is the method used to restart the game following this infraction, providing a fair opportunity for the opposing team as a consequence of the unauthorized substitution.