The word “documentary” was invented in 1926 by the Scottish filmmaker John Grierson, who founded both the British and the Canadian National Film Boards.  He defined the documentary as “the creative treatment of actuality.”

WHAT IS A “MOCKUMENTARY”?

This is a funny word used to describe a fake documentary, usually done for comedic purposes, but using the conventions of the real thing.  You may know of Rob Reiner’s This is Spinal Tap (1984), which more-or-less launched the genre.  Actors Christopher Guest, Michael McKean, and Harry Shearer (the voice of Principal Skinner, Mr. Burns, and many others on The Simpsons) went on to do many mockumentaries including Best in Show (2000) and A Mighty Wind (2003).

In This is Spinal Tap the trio plays a pretentious and very dumb English pop group from the sixties, now a heavy metal band and declining in popularity.