Worldbuilding
Building a coherent fictional world — geography, history, cultures, rules — and the art of revealing it without explaining it.
Worldbuilding names the design of an imaginary world in all its dimensions: geography, history, languages, religions, economy, natural or magical laws. It's the flagship discipline of fantasy and science fiction, but every novel builds a world — a Normandy village too.
The genre's law is the iceberg's: the author must know ten times more than they show, and the submerged mass is what gives the visible part its density. Successful worldbuilding reveals itself through use — an unfair tax says more than a chapter of political economy — and keeps its promise of coherence: readers forgive dragons, never broken rules.
Example
Miéville's New Crobuzon: an entire city reassembled from dockside grime and "remade" bodies.