Npr.org just posted an article on worldbuilding in fantasy series written by Saladin Ahmed, author of Throne of the Crescent Moon (Canada, USA, Europe). Here's a teaser extract:
Roughly put, world-building is the attempt to describe an invented, fantastic world by cataloging that world's history, geography, languages, religions, economy and so forth. It's a way of nudging the reader into Coleridge's "willing suspension of disbelief" through the accumulation of telling details. It sets readers and writers asking and answering a sometimes jarring array of questions, ranging from "Does this world have (a) God(s)?" and "Does it hold true good and evil?" to "How fast do the boats go?" and "What are the orcs' loincloths made out of?"
Not all novelists, nor all readers in the field, are interested in such literalism and mundane detail, of course. Some of the most talented and challenging fantasy writers of recent years have indicted the genre's world-building fetish. "How can we map every corner of a nonexistent place?" acclaimed British novelist China Mieville has asked. "Why do we want to?" And M. John Harrison, one of contemporary fantasy's most inventive writers, raised quite a stir a few years back when he raised doubts about "the psychological type of the world-builder," famously disparaging world-building as "the great clomping foot of nerdism."
But at its best, work that prioritizes world-building offers pleasures that just can't be found in other sorts of literature, the joy of traveling to, as Tolkien put it, "a Secondary World which your mind can enter." The type of immersion that a massive built world provides is unique. It's an almost physical sense of getting lost somewhere that isn't home, but which comes to be home. A sense that one is walking, sometimes even dancing, on a tightrope between the fantastic and the mundane. As with the Thousand and One Nights, which so often — and yes, clompingly — mentions things like which vegetables were just bought or who the monarch was at a given time, the modern fantasy novel's nerdy attendance to world-building gives it a strange mimetic heft not present in, say, fairy tales.