How must the numbers on a player's uniform appear?

The requirement for the numbers on a player's uniform to contrast from the uniform ensures that they are easily visible to referees, players, officials, and spectators. Clear identification of players through visible numbers is crucial for fairness and accuracy in officiating the game. If the numbers blend in with the uniform colors, it becomes challenging to distinguish players, which can lead to confusion during play and when keeping track of statistics or substitutions.

While size and color might play a role in visibility, the primary focus is on the contrast to guarantee that the numbers stand out against the background of the uniform. This contrast is what helps maintain the flow of the game and the integrity of the rules.