The IAON is a place in the realm of President Businesses' office and this takes a big part in the movie.
It is first shown when Lord Business wants to throw Bad Cop out the window, literally.
Then when Emmet is trying to escape the battery, he goes into it with the Piece of resistance and comes into the real world.
The boy uses a tube, leading back to the IAOS to get Emmet back on the fight.