That's the "Expanded Universe," made up of novels, comics, games, and a few other things.
The EU is authorized and enforced (rigidly) by Lucasfilm, but is not considered actual canon. Only the "Episodes" are canon; the six movies and their novelizations (the Ewok movies, cartoons, and the holiday special are also excluded).
I guess my real complaint WRT the way Lucas runs the show is that, if you're going to bother enforcing
a continuity, then you should follow it. Instead, Lucasfilm's rigid plotting of the continuum from The Golden Age of the Sith
applies to everyone except Lucas.
I'd really like to see Lucas holding himself to the same standards as the people he lets into his universe, but he just refuses, and Lucasfilm is too cowed to dare
With the cohesion of the EU, the GFFA has the potential to be something that's (to my knowledge) never been done successfully in fiction ever before; a truly continuous and cohesive shared-universe
. But instead, Lucas is resigning all of the EU (and even great chunks of his own
movies) into the quasi-official real occupied by Star Trek and Babylon 5 novels.
It's like I always say: When the going gets tough, the tough . . . switch to artillery.