The Changing Shape of Cinema: The History of Aspect Ratio

Ever wondered what the "Screen format" field in the movie detail page is? What it means, what it refers to?

I'm assuming most people these days are already clued into letterboxing etc., but if you're not or have always wondered "what those black bars" are on your TV screen, let me direct you to this educational video from FilmmakerIQ breaking down the history of the Aspect Ratio...