How Movies Changed Aspect Ratios Over Time

Probably the best wrinkle in aspect ratio history is how 16:9 came about: old 4:3 movie theatres birthed 4:3 television sets, which stopped people from going to 4:3 movie theatres, which made 4:3 movie theatres go widescreen to offer something different at home (which also eventually gave way to widescreen TVs). [FilmmakerIQ]