This is how the designers and engineers at Apple roll: They roll.

They take something small, simple, and painstakingly well considered. They ruthlessly cut features to derive the absolute minimum core product they can start with. They polish those features to a shiny intensity. At an anticipated media event, Apple reveals this core product as its Next Big Thing, and explains—no, wait, it simply shows—how painstakingly thoughtful and well designed this core product is. The company releases the product for sale.

Then everyone goes back to Cupertino and rolls. As in, they start with a few tightly packed snowballs and then roll them in more snow to pick up mass until they’ve got a snowman. That’s how Apple builds its platforms. It’s a slow and steady process of continuous iterative improvement—so slow, in fact, that the process is easy to overlook if you’re observing it in real time. Only in hindsight is it obvious just how remarkable Apple’s platform development process is.

One example is Apple’s oldest core product: Mac OS X. It took four difficult years from Apple’s acquisition of NeXT in 1997 until Mac OS X 10.0 was released in March 2001. Needless to say, those four years were… well, let’s just say it was a difficult birth. But from that point forward, Mac OS X’s major releases have appeared regularly (especially by the standards of major commercial PC operating systems), each better than the previous version, but none spectacularly so. Snow Leopard is vastly superior to 10.0 in every conceivable way. It’s faster, better-designed, does more, and looks better. (And it runs exclusively on an entirely different CPU architecture than did 10.0.) But at no point between the two was there a release that was markedly superior to the one that preceded it.

Next, consider the iPod. It debuted in the fall of 2001 as a Mac-only, FireWire-only $399 digital audio player with a tiny black-and-white display and 5 GB hard disk. The iTunes Store didn’t exist until April 2003. The Windows version of iTunes didn’t appear until October 2003—two years after the iPod debuted! Two years before it truly supported Windows! Think about that. If Apple released an iPod today that sold only as many units as the iPod sold in 2002, that product would be considered an enormous flop.

Today you can get an iPod nano for $179 that’s a fraction of the original iPod’s size and weight, with double the storage, a color display, video playback, and a built-in video camera. Apple took the iPod from there to here one step at a time. Every year Apple has announced updated iPods in the fall, and every year the media has weighed in with a collective yawn.

There’s never been one iteration of the click-wheel iPod platform that has completely blown away the previous one, and even the original model was derided by many critics as unimpressive. The iPod shows, too, how Apple’s iterative development process doesn’t just add, it adapts. Remember those third-generation iPods from 2003, with four separate buttons above the click wheel? Turns out that wasn’t a good idea. They were gone a year later. Remember the iPod Mini? It had no new features, and wasn’t even much cheaper— but it was way smaller.

The iPhone is following the same pattern. In 2007 it debuted with no third-party apps, no 3G networking, and a maximum storage capacity of 8GB. One year later, Apple had doubled storage, added 3G and GPS, and opened the App Store. The year after that, Apple swapped in a faster processor, added a compass and an improved camera, and doubled storage again. The pattern repeats. We may never see an iPhone that utterly blows away the prior year’s, but we’ll soon have one that utterly blows away the original iPhone.

That brings us to the iPad. Initial reaction to it has been polarized, as is so often the case with Apple products. Some say it’s a big iPod touch. Others say it’s the beginning of a revolution in personal computing. As a pundit, I’m supposed to explain how the truth lies somewhere between these two extremes. But I can’t. The iPad really is The Big One: Apple’s reconception of personal computing.

Apple has released many new products over the last decade. Only a handful have been the start of a new platform. The rest were iterations. The designers and engineers at Apple aren’t magicians; they’re artisans. They achieve spectacular results one year at a time. Rather than expanding the scope of a new product, hoping to impress, they pare it back, leaving a solid foundation upon which to build. In 2001, you couldn’t look at Mac OS X or the original iPod and foresee what they’d become in 2010. But you can look at Snow Leopard and the iPod nanos of today and see what they once were. Apple got the fundamentals right.

So of course this iPad—the one which, a few years from now, we’ll refer to off-handedly as the “original iPad”—does less than we’d hoped. That’s how the people at Apple work. While we’re out here poking and prodding at the iPad, they’re back at work in Cupertino. They’ve got a little gem of a starting point in hand. And they’re beginning to roll.

[John Gruber is the author of Daring Fireball. A version of this piece appeared as "Apple's Constant Iterations" in the April 2010 print issue of Macworld.]