A purifier is a device or substance that removes unwanted materials from something to make it cleaner or safer. Water purifiers filter out dirt, bacteria, and chemicals so the water tastes better and won't make you sick. Air purifiers pull dust, pollen, and other particles out of the air in a room, which helps people with allergies breathe more easily.

Different purifiers work in different ways: some use special filters that trap tiny particles, others use chemicals to kill germs, and some use ultraviolet light to destroy harmful germs.

You might have seen a water purifier attached to a kitchen faucet or a portable air purifier sitting in someone's bedroom. In science labs, researchers use highly specialized purifiers to remove even microscopic contaminants from their experiments. The goal of any purifier is the same: take something that contains unwanted materials and remove them, leaving behind only what you actually want.