They extract excess moisture from indoor air, making it comfortable and healthy for occupants.

By controlling the relative humidity level in your home, dehumidifiers:

1. Protect walls, floors and furniture from water damage.

2. Prevent the growth of fungus, dust mites, and mildew, which thrive in damp environments and trigger allergies.

3. End moldy, stale odors that can pervade a home.

Whole-home dehumidifiers are the most expensive models, costing between $1,000 and $2,000. They typically are fixed units professionally installed and connected to existing duct work in a home's central air or heating system.

Portable dehumidifiers, which you simply plug in to operate, are the most popular models and available at big box hardware stores and major department stores.

There are many advantages to using portable dehumidifiers over fixed ones. Advances in technology make these dehumidifiers easy to use, affordable and effective at improving your home's air quality.

But not all portable dehumidifiers are the same. Here is a look at common types of portable home dehumidifiers, how the units work, and features to shop for in a new dehumidifier.

The bottom line for consumers is to pick a unit that is efficient and effective at reducing indoor humidity and keeping it at optimal levels.