Like many things, it's a product of reviewing a lot of materiel and researching what other folks write on a subject. In some senses, it's all trivia if you're

Like many things, it's a product of reviewing a lot of materiel and researching what other folks write on a subject. In some senses, it's all trivia if you're not making movies, but it can be fun. There are plenty of textbooks out on the subject, and about any college textbook can give you an overview of the technical stuff and the general history. Personally, I've read a lot about film criticism and made some movies. Both taught me a lot. I was writing a book for a PhD in literature that focused heavily on film as literature, and took a bunch of graduate classes discussing it. I also made a lot of short films and worked on other peoples' films as well. Both of those paths can teach you a whole lot about film, depending on what you're interested in. But that's no different than any other thing that people might know about. I know a lot about web-oriented programming tools, because I have to do it every day. It's just the product of reading a lot of books and daily practical application. Film just has fewer obvious daily practical applications.