When I began writing fantasy, one of my goals was to present an imaginary world with depth enough to satisfy my own standards as a reader.  When my first novel The Burning Stone 1 was released in 1987, a  reviewer for Locus Magazine complimented me on creating "a lived-in world, and lively one". So what (besides geography and history) makes for a "lived-in, lively" fantasy world ? The definitive factor is what I like to call "deep structure".  Deep structure encompasses a range of background details which have created the situation your characters find themselves at the start of your story.  Contributing factors include customs, traditions, codes of behavior, technology, art, philosophy, and metaphysics (especially important with regard to how magic works in your world) Deep structure isn't meant to present itself as full-on exposition (the infamous info-dump).  Ideally, it should surface in the form of casual referencing. The technique of sel...