Info Dump

[Shaun]

One of your worst enemies as a writer is none other than Captain Info-dump himself. He's also known as Bob, which stems from that saying "As You Know Bob".

So what exactly is Info-dump?
Info-dump is probably the most common mistake made in fantasy and science fiction literature, and as of late it has become blindingly common in science fiction (the reason for this being that the Age of Style--as Asimov coined the era of SF literature we are currently in--often uses concepts and ideas that otherwise would be impossible to show to a reader, but must be explained).
Info-dump is basically that paragraph or paragraphs, or even pages of information provided babbling on about something that isn't necessarily related to the plot. Essentially, it's "telling" the reader something that you think is of vast importance. An example of this might be to tell the reader how the religion of your fantasy world works by going into the caste system, the different levels of religion, etc. By the time you finish you've succeeded in completely irritating your reader to the point where they've likely tossed the book aside.
Info-dump is also, as I said, part of that "As You Know Bob" syndrome. This is where a character, usually secondary, goes off and tells the main character a bunch of information. Think Gandalf. Now, as much as we all love that adorable White Wizard--well he was Gray first and became White for reasons that I still to this day think are racist--he is, unfortunately, the King of Gab in fantasy. If you haven't read the books, please do. Realize this, though. Tolkien was writing in a time when Fantasy was mostly nonexistent. It existed, but it wasn't like it is today, and with the depth of his world it was entirely necessary. He was called the Father of Fantasy for a reason everyone.
So, if you have Lord of the Rings handy, pick it up and start looking for anything that involves Gandalf discussing the ring. Take the scene where Gandalf explains where he has been and what he has learned about the ring. He tells about how the ring left Isildur, came to Gollum, left Gollum, etc. There's more to it, of course, but Gandalf just goes on and on about the ring and everything imaginable about the ring. Granted, in real life, this might actually take place, but in a book, the reader cannot be bothered with these sorts of scenes--not in today's literature at least.
Or perhaps you find yourself wanting to explain how that new-fangled faster-than-light engine works. Don't. In fact, FTL drives are so absurdly common today that unless you have some amazingly new and fascinating idea that has never been done before and actually sounds plausible, you shouldn't go beyond saying it's and FTL drive. Yes, you can give it another name, but simply define it as an FTL drive.

If all of that above didn't make much sense, then take a look at what SFWA's Turkey City Lexicon has to say about the matter:More...

"[Info-dump is a] Large chunk of indigestible expository matter intended to explain the background situation. Info-dumps can be covert, as in fake newspaper or "Encyclopedia Galactica" articles, or overt, in which all action stops as the author assumes center stage and lectures. Info-dumps are also known as "expository lumps." The use of brief, deft, inoffensive info-dumps is known as "kuttnering," after Henry Kuttner. When information is worked unobtrusively into the story's basic structure, this is known as "heinleining."

Make sense now?

What can you do about info-dump?
There is a lot. First off, like all rules of writing, there is a careful balance in how much you can get away with. Of course you can info-dump a little. It would be ridiculous to assume that you could never convey information to the reader that if coming from your characters would sound completely idiotic. If you read modern fantasy or SF you'll notice that info-dump is used in moderation. It has to be, otherwise writers would be spending hundreds of pages trying to show you everything. Part of the reason I took up this issue is because it is related to the previous issue of "Show, don't tell", all for very obvious reasons.
So, here are ways to address info-dump.
--Give away little bits of information from time to time about your world or the characters, but only when it doesn't influence the flow of the story. In the case of short stories, it's wise to avoid info-dumping more than once, and probably no more than a couple of sentences. Giving just enough information to give the reader context is enough. In novels you can do it quite a bit more, but at the same time it cannot influence the flow of the story. The characters, plot, and entertainment value take precedence over anything else.
--Only give away information that you have to. If you can get away without explaining something, then by all means do. Sometimes, though, you might find that you can't continue with the story without trying to explain something. In that case, explain it, but be extremely brief about it and make sure it is interesting. Again we look to SF as an example. I recently read a book called Spin State by Chris Moriarty (which you should pick up). In it Moriarty uses a lot of string theory and quantum theory concepts. Rather than simply explaining either theory, he goes into the general idea of how things work. He doesn't give us blinding explanations that go nowhere, but he makes tasteful decisions on where to info-dump, usually when a character is using a particular thing. Most of you wouldn't have a clue what "streamspace" is. I didn't, and the way he explained it worked out well.
--Avoid long winded attempts to explain something to the reader. This is info-dumping at its worst.
--Avoid using secondary characters to tell loads of information to your main character. We'll call these "Gandalf Moments".
--Try to be interesting when you do info-dump. If you make the information fun for the reader, then the reader won't mind being 'educated'. Peeps by Scott Westerfeld is a great example of this. Westerfeld put in occasional blurbs of information about real parasites and viral infections from his point of view, with a tinge of humor thrown in. This is a wonderful way to bring information to the reader. In Peeps, the information is detached from the story, so essentially you could skip those sections, but they worked because they were interesting. Some novels, such as Spin State by Christ Moriarty, and even Harry Potter by J. K. Rowling, do things where they tell you information in quotes or blurbs from newspapers, real or otherwise. In Spin State, Moriarty begins each major section with a quote related to the quantum foundations of his world. They all look so real and sound like true quotes from a scientific paper that you don't question them. Rowling, on the other hand, uses things like the Daily Prophet and the like to bring about information to the characters in a fun and interesting way.

Now, all in all, info-dumping is evil, much like Apple Computers, but that's for another time. You have to understand that giving the reader information that sounds lovely and fascinating to you doesn't necessarily mean the reader is going to like it. Rich detail is great, but when it hurts the story itself then you have a problem.
So, avoid info-dump as much as necessary. Occasional info-dump sessions are fine, in moderation and in small quantities.

Happy writing!