October is National Popcorn Poppin’ Month, and don’t let the fact that it’s almost over stop you from enjoying some of these treats.

Popcorn, a type of maize or corn, is a type of grass. It’s a whole grain, and a cup of air-popped popcorn without toppings contains only 31 calories per cup.

The popcorn pops, The Popcorn Board says, because it has a thicker hull that allows pressure from the heated water in the corn to build and eventually burst open. The starches in the corn become gelatinous while being heated and, when the hull bursts, spill out and cool.

The two basic shapes of popped popcorn are snowflake and mushroom.

Snowflake-shaped popcorn is used in movie theaters and other snack counters because it looks and pops bigger.

Mushroom popcorn is used in confections because it doesn’t crumble.