CGI is the pictures in films and television that a computer builds, rather than a camera filming a real street, creature, or object. The letters stand for computer-generated imagery. A dragon that never stood on a set, a crowd of thousands who were never there, a city that sinks in one shot — that is CGI. People also use CGI rather loosely for “the computer part of the effects,” even when some of the work is painting or sticking several pictures together. In careful talk, CGI is the computer-made image itself. This is everyday film talk now. The same three letters mean other things in computing; this entry is the film and TV sense.