AT THEIR MOST BASIC, dehumidifiers, humidifiers and air purifiers might seem like relatively similar devices. All are boxy, sometimes expensive appliances that help correct issues with your air quality with the help of some form of filter. Yet each serves an extremely different function. Here, a guide to their most important characteristics and tips on how to use them best.

A Tall Drink of Water

In the winter, if you’re spending most of your time cooped up inside next to heaters, your skin can become incredibly dry. It’s also common to experience dry eyes, chapped lips, or, worse, regular nosebleeds. A humidifier will add moisture to the air in your home, and can help those afflicted, according to Dr. Dawn Davis, a dermatologist at the Mayo Clinic in Rochester, Minn. While all humidifiers pull from a reservoir of water, they operate in one of two ways. Ultrasonic humidifiers use rapid vibrations to propel a mist of water into your air. Evaporative humidifiers, meanwhile, heat the water until it is steam, then use a fan to push it through a filter. Both types work, though ultrasonic ones, like this Levoit Classic 300s, tend to run more quietly and can be taken apart more easily for cleaning. Make sure to wipe down all parts of the humidifier daily and sanitize the tank with a vinegar solution at least every other week so no microorganisms can grow in the standing water.