Why Do Movie Theaters Serve Popcorn?

Was it just being in the right place at the right time that made this snack so popular at the movies?

Why is popcorn associated with movies? - Quora

Movie Theater Butter Popcorn

Movie theaters get creative with concessions

Fresh Popped Movie Theater Popcorn

A small local movie theater me uses reusable metal bowls for the popcorn : r/mildlyinteresting

Gold Medal Launches New Self-Serve Popcorn Products - Boxoffice

Movie Theater Food Guide

AMC Theatres Ready to Eat Popcorn, Classic Butter

Self-Serving Popcorn Machine, Is this what heaven looks like?, By Consequence of Film