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Air purifiers, humidifiers, dehumidifiers — chances are you’ve heard of all of these before and you know that they do...something for the air in your home. Knowing what exactly each of them do is another story.

If you find yourself using these three terms interchangeably (don’t worry, we’re guilty, too), we talked to two doctors about what makes each of these three machines different and why you might need a dehumidifier in your home.

With so many machines on the market, it can be easy to think there’s little to no difference between them. “People tend to say that something you stick in your house to modify the environment...must all be the same but...certainly it’s not,” said Georgia-based provider Dr. William Nish.

Nish and Dr. Robert Naclerio, otolaryngologist at Johns Hopkins Medicine, broke down the difference in simple terms: An air purifier takes particles out of the air; a humidifier puts water into the air; and a dehumidifier takes water out of the air.

Since the start of the pandemic, we’ve heard about the importance of using air purifiers with HEPA filters to remove virus-sized particles and improve the indoor air quality inside your home. “Even though you look at the air, it can have particles and other things within it that can cause trouble and so people clean the air from that,” Naclerio explained.

Humidifiers come in both cool and hot air options, but Nish noted that the temperature makes minimal difference in their overall performance. “They both put out mist into the air to increase the humidity and to help people who are sick with mobilizing their secretions and maybe help them feel better,” he said.

A dehumidifier does a similar job as an air purifier in that it takes things out of the air. However, instead of removing particulates, it removes water.

While a dehumidifier is likely most useful during summer months when humidity is high in most places, it can still be useful during colder, drier months in rooms like a basement that have a tendency to have high humidity levels, Naclerio and Nish explained.

Higher humidity levels can promote growth of mold and dust mites, neither of which are welcome friends in any home. “Molds also make toxins that can go ahead and create symptoms and problems for patients,” Naclerio told us.

An increase in humidity levels can also be damaging to your furniture or appliances, Nish added. Ultimately, using a dehumidifier can help save you time, money and frustration in the long run.

The main tip for buying the right dehumidifier is a simple one: Be sure to buy the right size for your space.

“If you have one that’s really too powerful or too big for a small room, then you’re wasting a lot of energy and money in trying to because it overpowers the room. If you have one that’s too small for a big room, then it’ll just run all the time and won’t really do the job for you,” Nish said.

Also, for larger rooms, he recommends setting up a pump that flows excess water outdoors because constantly emptying the storage bin of water can be tedious.

This option has a 16-ounce tank and a range of a little over 200 feet, making it ideal for a smaller room. When the water tank is full, it has an auto shut-off feature so you won't have to worry about overflow or spills.

"This is definitely worth every penny and the amount it would cost to buy one for every room in my house is way less than buying one fancy name brand one that cost over $300!!" one verified five-star Amazon reviewer shared.

Dubbed the "Moisture Maniac" by the brand, this dehumidifier holds up to 22 pints of water per day and has a sleek design with built-in wheels and a handle for convenient portability. This option also comes in 3,000-square-foot and 4,500-square-foot options for larger rooms. It has a 4.6-star average and almost 9,700 verified five-star ratings.

With this Toshiba dehumidifier, you can set up your desired humidity level and the machine will maintain your setting throughout the day. You can easily move it from room to room with its four-wheel design.

"This dehumidifier is a powerhouse! I use it in my basement and it can pull 3 bins full of water out in 24 hours, more if I was able to check it more frequently," raved one Home Depot verified five-star reviewer.

Currently trending at Lowe's, this dehumidifier also has a 4.2-star average rating. It also has an air filter and a filter indicator that lets you know when to wash it. After just two hours of use, one reviewer saw an impressive difference in the amount of moisture levels in the air and said the air quality was "noticeably different."

This Amazon bestseller comes in two different sizes: a 1,500-square-foot version for medium to large rooms and a 4,500-square-foot version for extra large rooms and basements. The smaller size removes up to 22 pints of water from the air per day and the larger size removes up to 50 pints. Tens of thousands of verified five-star reviewers love this machine for how easy it is to set up and the rate at which it reduces humidity in their spaces.

This 30-pint dehumidifier from Honeywell is suitable for rooms up to 3,000 square feet. It displays the humidity level on an LED digital display and has a smart digital humidistat control system that's meant to automatically sense levels of moisture in the room and activate dehumidification. One verified five-star reviewer loves how quiet the machine is and even provided video evidence so you can hear (or not hear) for yourself.

This Frigidaire dehumidifier can take up to 50 pints of water out of the air each day. It also has other nifty features like custom humidity controls, three fan speeds, auto shut-off and a full tank alert so you know when its limit has been reached. With a 4.6-star average, several Walmart reviewers praised the machine for its ease of use and lack of loud operating noise.

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Kamari Stewart is a Commerce Editorial Assistant for Shop TODAY.