A frost-free freezer is one that has an internal mechanism to avoid frost build-up. In theory, this means that you would never have to defrost the freezer. They work through a system of fans. As warm air enters the freezer, it is blown away before it has a chance to freeze and create frost.

The frost-free freezers eliminate frost by raising the temperature inside the freezer a few times a day, from about 0 degrees to 32 degrees. While this still keeps your food at a freezing temperature, it prevents any free-floating water particles from forming into ice, instead collecting them and siphoning them out of the freezer.