Why does popcorn pop?

Lights…camera…action! Popcorn is a snack food star. But what is it, and why does it pop?

Popcorn kernels come from a certain type of corn. Popcorn kernels are seeds. Inside the hard shell is a small amount of water. When the kernels are heated up, that water turns to steam. The steam takes up more room than the water, and the hard shell traps it so the steam has nowhere to go. Until…POP! The steam breaks open the shell, and you now have a tasty snack.