Here's the world-building blog entry.
One of the five things she lists--and one we've all got to watch for, right-- is this:
2. Never world-build through infodump.
(N.b., there is a difference between an "infodump" and "exposition." Robin McKinley world-builds through exposition at the beginning of Spindle's End; Diana Wynne Jones world-builds through exposition at the beginning of Howl's Moving Castle. These are both markedly different from the infodump world-building at the beginning of the book I'm reading right now, James White's Ambulance Ship.)
I will say that the difference between infodump and exposition may come down to the talent the writer has with prose and the voice used. I read and loved both Spindle's End (one of my very fave fantasy novels, and perhaps my favorite based on a fairy tale) and Howl's Moving Castle (which also made for a terrif animated film by Miyazaki).
Years ago, the first pages of Spindle's End captivated me in the bookstore and I hurried home to read it. That's exposition that grabs, not infodump that bores. But it may be subjective, too. What you find exhilirating exposition may make me yawn. Ultimately, any writer who really has a voice and a handle on craft should be able to make the delivery of narrative into exposition rather than infodump. :::shrug:::
I know when I'm reading stories as an editor, I look to see if the information is strongly attached to character. If I'm getting the sense of a person's POV, even if it's a longish stretch of narrative, if it has that personality filtering through, then I don't count that as infodump. And it could be the voice/personality of the author or of a particular character. But I need to sense LIFE.
Infodump has a flatness, a sort of, "Here it is: I think you need to know this, so there. Read it. Now I can go on with the interesting stuff."
If it's compelling exposition, it has a sense of vibrancy, of a living thing behind it. It has a bit of depth or snap or sparkle--something that says this isn't just a report for a teacher or dry information. The difference, say, between:
The planet Alomus, a vacation destination for that sector of the galaxy and known throughout the cosmos for its dyes, was an astonishingly vivid blue. The discovery of Alomus had changed human wedding traditions. Brides stopped wearing white and started wearing Alomus blue. Honeymoon bookings for trips to Earth plummeted and Alomus became the intergalactic Niagara. The riches that the dyes and tourism brought in turned the planet into something that an old historian might have termed a den of sin.
That's not utterly horrible, and it does convey information about the planet, as well as a bit about the voice ("astonishingly" and "den of sin"), but it's not all that vivid itself.
Alomus glowed the exact blue of Korina's grandmother's eyes on those days when her grandmother was up to no good. On the ultimate day of mischief for her grandmother--the day she married Korina's grandfater--the bride had worn a gown of Alomus blue. They'd had to sell one of their vacation homes to afford it. There was irony there. Alomus, pleasure planet, the number one honeymoon hotspot, and the provider of priceless blue dyes. Why did everything end up having something to do with her dead grandmother and the planet waiting for her to land?
Alomus blue. Now, there was a color for dreaming. Deep and alive, so famous and coveted that a citizen of my home planet would happily spend five years of overtime pay to afford a robe dipped in the dyes only found within the sea-floating vegetation of the pleasure planet. So desired that the number one justification for murder on the planet was poaching of the dye-waters. The number two was seduction of a newlywed.
Three different ways of saying a planet is blue and three different voices used in saying it. Granted, none of those bits is long enough to really count as infodump, but it was for example. Infodump would go on in the manner of example one--just throwing stuff out there. The others hint at things pertaining to people. To the characters viewing the planet.
Anyway, go see what Sarah M. has to say.