Popcorn, a variety of corn with small, hard kernels. When the kernels are heated, moisture inside them turns to steam. Kernels of popcorn, unlike kernels of other types of corn, trap the steam so that as steam pressure builds up, the kernels explode. Each exploding kernel turns inside out and expands into a fluffy white or yellow mass. Popcorn is a starchy food, eaten as a snack. It usually is buttered and salted, or coated with caramel or molasses. Popcorn also has been used as a packing material.

The popcorn plant resembles the sweet corn plant but is shorter, and bears many small ears. There are about 25 varieties of popcorn. Main types are rice popcorn, with pointed kernels, and pearl popcorn, with rounded kernels. Popcorn is cultivated like sweet corn. It was an important food of the Indians of the southwestern United States and Mexico in prehistoric times.

Popcorn is Zea mays everta of the grass family, Gramineae.