Why do you need a mattress protector?
A mattress protector is a piece of removable bedding that protects a mattress by sitting on top of it or encasing it. Some mattress protectors also provide protection from allergens and irritants such as dust mites, bed bugs, mold, and dead skin for the person sleeping on the mattress (like dandruff).
Are mattress protectors necessary?
There's no need to buy a mattress pad if you're buying a new mattress (assuming you are happy with the mattress). A mattress protector, on the other hand, is practically mandatory. It's cheap, protects your investment, has no visible effect, and shouldn't significantly alter the feel of your mattress.