A mattress protector is a removable cover designed to fit over a mattress, providing a barrier against spills, stains, and allergens. It helps to keep the mattress clean and can extend its lifespan by preventing damage from everyday use. Most mattress protectors are made from materials that are waterproof or water-resistant, which makes them effective against liquid accidents. They can also be hypoallergenic, helping to reduce dust mites and other allergens, making them a good choice for people with allergies or asthma.