Popcorn kernels pop because an outside heat source converts water to steam. When the pressure from the steam becomes too great, the outer hull explodes and the result is a fluffy taste treat. It makes no difference to the popcorn kernels how the heat arrives, as long as it stays hot enough long enough to generate the steam. Historically, this was achieved by exposing the kernels to an open fire or perhaps using heated vegetable oil in a pot. Neither method proved to be especially reliable or healthy.

In the 1970s, the popcorn industry underwent a remarkable makeover, resulting in the introduction of gourmet popping corns and new ways to pop them for maximum yield and flavor. Around the mid-1970s, the first hot air popper for home use was introduced. Numerous variations of the air popper appeared on the market shortly afterwards. Some companies, such as Hamilton Beach, were already established in the appliance business, but others created air poppers by modifying their existing hair drying product lines.

A hot air popper works by spinning raw popcorn kernels in a central chamber. As the kernels reach the outside vanes, hot air generated by an electrical element is introduced. Within a few minutes, the small amount of water trapped in every kernel converts to steam. When the fibrous hull can no longer resist the pressure, the entire kernel explodes and the starchy fibers inside combine with the air to form the finished product. Since the popcorn is now much lighter, the air popper's circulating airstream blows it out of the chamber.

Once the kernel has popped, the finished popcorn travels through a plastic chute until it lands in a waiting bowl. A typical air popper may also contain a special compartment for melting butter or adding seasonings. Most air popper models also include a means for measuring additional batches of popcorn. Since no oil is required, an air popper can generate several batches of popcorn in a row without stopping.

There are some who say an air popper produces a healthier batch of popcorn because it does not add oil to the process. Others suggest that the amount of oil used in other popcorn makers is negligible, and the additional moisture and seasonings makes the finished product taste better. Proponents of the air popper method suggest using a gourmet popping corn with a higher moisture content to avoid dryness. A hot air popper generally produces fewer unpopped kernels compared to oil-based poppers, and the individual kernels are often fluffier.