A dehydrator is a machine that removes water from food to preserve it. Fresh fruits, vegetables, and meats contain lots of moisture, which bacteria and mold need to grow. A dehydrator uses warm, moving air to slowly dry out the food, making it last for months or even years without refrigeration.

Inside a dehydrator, trays of sliced apples, banana chips, or beef jerky sit in gentle heat (usually between 95 and 165 degrees Fahrenheit). A fan circulates air around the food, carrying away moisture hour after hour. After several hours or even a full day, the food becomes dry and chewy but keeps most of its nutrients and flavor.

People have dehydrated food for thousands of years by leaving it in the sun or hanging it in the wind. Modern electric dehydrators simply make the process faster, cleaner, and more reliable. Hikers love dehydrated meals because they're lightweight and don't spoil on long trips. Gardeners use dehydrators to preserve their tomato or pepper harvests. You can even make your own fruit leather or dry herbs.