World building

Someone else asked me how I go about world building when writing fantasy or science fiction or historical fiction. (I’ve written all three.) Once again the question made me go all inarticulate and respond randomly and lamely: “How do I breathe?” “How does a butterfly flap its wings?”

Clearly I need to figure out how I go about world building. I’m fascinated by writing process and this is a large part of mine. I have to quit it with the inarticulate spluttering.

So those of you have written novels not set in this world—how did you go about your world building? Or, to refer to a recent discussion on Gwenda’s blog, what story do you tell yourself about your world building?