For a century, the technology of filmmaking remained largely the same. Cameras photographed images on physical rolls of film (as did the microphones for soundtracks). Those images and sounds were edited into sequence by physically cutting and rejoining pieces together. The finished reels were then spooled into a projector and screened inside a theater. Year by year, project by project, George Lucas pushed Lucasfilm to change that process.
Source: Clones at 20 | 4 Ways Star Wars: Attack of the Clones Helped Change Filmmaking | StarWars.com