A substitute, or replacement, refers to something that takes the place of another item or person. This can occur in various contexts, such as in cooking, where one ingredient is used instead of another, or in sports, where a player is replaced by another during a game. Substitutes are often chosen based on their ability to fulfill similar functions or roles. In education, a substitute teacher steps in for a regular teacher who is unavailable. This ensures that students continue their learning without significant disruption. Substitutes can also apply to products, like using applesauce instead of oil in baking, providing similar results while accommodating dietary needs.