A "substitute" refers to something that takes the place of another item or person. In various contexts, it can mean a replacement for an ingredient in cooking, a stand-in for a teacher in a classroom, or an alternative product in a market. Substitutes can serve similar functions or provide comparable benefits, making them useful in many situations. In sports, a substitute player is someone who replaces a teammate during a game. This allows teams to manage player fatigue, injuries, or tactical changes. The role of a substitute is crucial, as they can impact the game's outcome by bringing fresh energy or different skills to the field.