A mattress protector is a removable bedding item that sits on top of your mattress to safeguard it from spills, stains, dust mites, and allergens. It acts as a barrier, preventing liquids and other contaminants from penetrating the mattress, which can help extend its lifespan. Mattress protectors come in various materials, including cotton, polyester, and waterproof fabrics, each offering different levels of protection and comfort.