While most of us love movies, we don’t necessarily know much about the little strips of celluloid that, for over a century, have made them possible. Though more and more movies are being made digitally these days, many filmmakers still insist on shooting on film, while others, though shooting digitally, are influenced by earlier film aesthetics. In the short video “What is Film,” YouTube user What Is delves into the most overlooked aspect of 20th century filmmaking: the film, itself.

In just over five minutes, the fascinating video touches on everything from aspect ratio and film stock to the chemical makeup of a film strip. Explaining how all the little bits and pieces—from the holes in the film (perforations) to the sprockets they latch onto—go together, the video is essential viewing for anyone who calls themselves a cinephile. Check it out above.

[h/t Gizmodo]

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