Popcorn is a snack made by heating dried corn kernels until they explode into puffy, white pieces. Inside each kernel is a small amount of water. When you heat the kernel, the water turns to steam and builds up pressure until the kernel bursts open with a pop, turning inside out into something dozens of times larger than the original seed.

Native Americans discovered popcorn thousands of years ago and shared it with English colonists, who were amazed by corn that could pop. For centuries, people popped corn in pots over fires or on stovetops. Today, most people use microwave bags or electric poppers, though the basic process remains the same: heat, pressure, pop.

The word can also describe other things that pop up suddenly and unpredictably. A popcorn storm produces scattered, brief bursts of rain that pop up here and there. When ideas or conversation topics keep popping up randomly, someone might call it a popcorn discussion, jumping from one thing to another like kernels bursting in a hot pan.