Movies, invented at the end of the 19th century, became one of the defining art forms of the 20th century, moving from flickering images of stage performers to CGI-based effects that could bring any fantasy to life.  Oxford Times film critic David Parkinson and publisher Laurence King have produced a new book called 100 Ideas that Changed Film, covering topics like technology (magic lanterns, handheld cameras, special effects, animation), genres (slapstick, epics,  expressionism, documentaries, blockbusters), historical events (the blacklist), as well as artistic developments like soundtracks and montage.  Well worth reading.