Popcorn was not originally welcome in movie theaters.

In the early 1900s, many theaters were designed to resemble elegant opera houses. Owners worried that popcorn would create noise, litter, and an atmosphere that felt too casual for their audiences.

At the same time, popcorn was becoming popular as a street snack because it was inexpensive to produce and easy to prepare with small steam-powered popping machines.

During the Great Depression, popcorn vendors often set up carts outside movie theaters, selling bags of popcorn to people waiting for the show. Theater owners soon noticed that audiences were bringing the snack inside anyway.

Eventually, many theaters began installing their own popcorn machines. The decision proved extremely profitable. Popcorn kernels were inexpensive, but the finished product could be sold at a much higher price.

The smell of popcorn is also part of the theater experience. When popcorn kernels heat and burst, they release a range of aromatic compounds created by browning reactions that produce nutty and toasted scents.

Food scientists later enhanced this aroma by developing butter-flavored oils and toppings. Many of these contain compounds such as Diacetyl, a molecule that produces a strong buttery smell. Because these aromas disperse easily in warm air, even small amounts can fill a theater lobby and stimulate appetite before the first bite.