How is a player determined to have committed a foul?

A player is determined to have committed a foul primarily through the act of making illegal contact with an opponent. According to NFHS basketball rules, various forms of contact can lead to a foul being called. This includes not only physical contact but also actions that hinder an opponent's ability to play the game properly, such as illegal screens or holding. The referee’s judgment on whether contact constitutes a foul is based on the nature and circumstances of the situation during gameplay.

In contrast, receiving a warning from the referee does not necessarily indicate a foul has occurred; it is often used in scenarios where the official feels a player is on the verge of committing a violation but has not yet done so. Exceeding the shot clock is a violation of game rules but does not involve player contact, so it would not be classified as a foul. Fouling oneself is a misunderstanding of the concept as it implies an action that leads to a player injuring or penalizing themselves, which is not recognized as a foul under the NFHS rules. Thus, making illegal contact with an opponent is the clear and definitive criterion for determining a foul.