The answer to 'what is a dehumidifier' is a device that helps control the humidity levels in a home or building. Dehumidifiers work by drawing in air from the surrounding environment, removing excess moisture, and then circulating the drier air back into the space.
Dehumidifiers are commonly used in damp or humid climates to help prevent issues like mold, mildew, and musty odors that can develop in high-moisture environments. They can also help improve indoor air quality and make the home feel more comfortable by reducing the sticky, clammy feeling that comes with high humidity.