Now that we’ve more-or-less defined “design,” since the working title of this series is Great Design, I better come up with a working definition of “great.”

Just about every product category has its blue-chip, gold-plated stars. Movie stars? Brad Pitt. Best rock song of all time? Sweet Home, Alabama, of course. Office chairs? The Herman Miller Aeron. Portable MP3 players? Clearly the Apple iPod.

What do these products have in common?

Brad Pitt can attract millions of people to the box office. He’s very good looking, and very charismatic, and it’s not even clear if he can act, but who cares?

Sweet Home, Alabama is one of the catchiest songs of all time. It’s extremely popular despite the fact that it’s impossible to sing or hum (the refrain requires harmony), the melody is awkward, and the lyrics include a couple of reprehensible lines defending Alabama’s racist and segregationalist governor George Wallace, but few people really notice the flaws, they just enjoy the song.

The Aeron chair became the symbol of high end office chairs. It’s expensive and looks like a giant cockroach, but when the directors of 24 need to show the canonical “super luxury office chair” for the White House, they use an Aeron.

And finally, the iPod. Ah, the iPod. It’s way more expensive than any competitive MP3 player. It has fewer features than the competition. The iPod nano, the tiny one that everybody’s raving about, is the only product I’ve ever seen that can be scratched beyond all recognition just by touching it lightly with your finger, and the shiny mirror back will be permanently covered in greasy fingerprint smudges from the moment you take it out of the elegant package until the battery wears out and you have to throw away the whole thing and buy another. But who cares?

The blue chip product in every category can usually be thought of as being popular despite obvious design flaws. Weird.

As the design gets better and better, as the product becomes more and more suitable to its users needs, it becomes more likely to be chosen by customers. So the 40GB MP3 player, all else being equal, will outsell the 20GB MP3 player. The easy-to-use phone will outsell the hard-to-use phone. All else being equal. That part is not weird.

But that only gets you so far, as Creative, makers of the unloved ZEN MP3 players, are learning the hard way. Despite having products that are better than the iPod by just about every reasonable metric, they are unable to even come close to Apple iPod’s dominant market share. They’re cheaper. They have more memory. They support more file formats. Etc. Doesn’t matter: they still have single-digit market share while iPod is probably in the 80s somewhere.

That’s because good design can only take you so far. Getting every aspect of the design perfect, making a usable product, making the right tradeoffs between price and functionality, between flexibility and ease of use, between weight and battery life, etc., etc., etc., is all really important, but the most it can possibly get you is to #2.

It’s like beauty. A wannabe model can be tall, with a perfectly symmetrical face, beautiful skin, lovely eyes, and perfectly straight white teeth, and still be considered unattractive. On the other hand, you can have a gigantic broken nose, or be completely lacking in eyebrows, or have a giant gap between your two front teeth, and still be People Magazine’s Sexiest Whatever of the Year.

How do you get to be #1? That’s the mystery here. And since certain markets (graphical operating systems, online auctions, and apparently MP3 players) seem to be winner-take-all markets, being #2 or #3 may not be good enough.

So this is what I’m talking about when I say “Great Design.” It’s that ineffable quality that certain incredibly successful products have that makes people fall in love with them despite their flaws. It’s extremely hard to pull off. I sure as heck can’t do it. But, if you bear with me, I think I have some theories as to what’s happening. While these theories do not exactly add up to a recipe for making good products into great products, they may give you a clue as to what’s going on when people go crazy about the Aeron chair or Julia Roberts.

Here’s the overall plan for this series of articles. First, I’m going to go through good design, namely, all the things you should know to get your design adequate given the current state of the art. Ease of use is a fundamental part of that so I’ll spend a lot of time on usability.

Later, once I’ve got all the obvious things taken care of, you’ll have a really usable design and one which meets your customers’ needs, and in fact, if you pay more attention to these usability things than your competitors, you may have the best design, but that’s not going to get you to #1.

“Every time I read Jakob Nielsen,” I wrote in 2000, “I get this feeling that he really doesn’t appreciate that usability is not the most important thing on earth. Sure, usability is important (I wrote a whole book about it). But it is simply not everyone’s number one priority, nor should it be. You get the feeling that if Mr. Nielsen designed a singles bar, it would be well lit, clean, with giant menus printed in Arial 14 point, and you’d never have to wait to get a drink. But nobody would go there; they would all be at Coyote Ugly Saloon pouring beer on each other.”

So in the final articles, roughly the last third of the series, I’ll peek under the covers at the black magic of great design. You may not be able to pull it off. It takes real talent, not just hard work. But at least I hope you’ll recognize some of the things that are going on that make certain gadgets, software, songs, movie stars, and office chairs make that leap from merely throroughly good to truly and significantly great.