Two years is a long time in the Internet world and even longer in mobile. So how has the Apple iPhone changed the world since its debut in July 2007?

That question may peeve many in the mobile industry. As some executives strain to point out at conferences and within conversations, the iPhone is nowhere near a mass phone and should not be the goalpost for every ball.

Fair enough. At 20 million phones -- out of the 4 billion or so in circulation worldwide " the iPhone does seem to be punching above its weight, at least in press coverage and marketing chatter.

And yet.

What the iPhone has become is a catalyst that has jump-started innovation across the phone-manufacturing business. It forced Research In Motion to produce better, more user-friendly BlackBerry phones. It energized LG, Palm, Samsung, Nokia and HTC to offer consumers a choice other than the staid candy-bar and QWERTY keyboard designs.

Don't believe this? Just line up mobile phones from 2000 to 2007. So ? did anything change? OK, maybe the cosmetics. After all, the Motorola Razr flip phone was a success. But where was the excitement over a new mobile phone?

So it bears repeating: The iPhone forced hitherto-complacent manufacturers to think twice -- once for themselves and once for their customers.

Indeed, what Apple brought to the table is a razor-sharp focus on the customer experience. The company realized consumers wanted to have their cake and eat it too -- a mobile computer that could enable talk and text and way more than that.

Another brilliant stroke was extending the software concept to mobile. Not only is the device that's important, but what's on the device equally so. Apple reinterpreted the mobile phone with the launch of its App Store.

At 65,000 apps - and 1.5 billion downloads - the App Store offers everything from news, games and credit-card processing to weather updates, recipes, accounting software and package tracking. What a brilliant move. Apple just made switching costs incredibly high for iPhone users to move to other phones.

Add to that content another plus -- the 300x250 screen that makes it possible to read news, watch videos, check email and open applications without much squinting and anguish. How many iPhone users now simply surf the Web on the phone instead of a computer, at least if they are not in the vicinity of one?

There's no other way to put it: the Apple iPhone has revolutionized the consumption of content on the mobile phone. And it has spawned scores of imitators who come close to the original but just don't have the x factor.

If anything, the Apple iPhone has untethered consumers from their computers, both desktop and laptop. Such freedom will surely do to computing what the mobile phone did to landlines -- render redundant the notion of physicality.

Sure, there's plenty to criticize about the iPhone.

There's the lack of a raised QWERTY keyboard. The inability to render Flash. The restrictions on buying music other than from the iTunes store. And the AT&T factor -- an irritant to some who find its network patchy and a non-issue to others who are willing to sacrifice unblemished coverage for a mobile lifesaver.

It's not often contemplated publicly, but imagine the possibilities if Verizon Wireless -- widely recognized as having the best network coverage nationwide -- had tied up with Apple to offer the iPhone instead of AT&T.

Finally, Apple needs to work harder in attracting the business user. It isn't just a matter of wooing business executives, but also their enterprises to support the iPhone infrastructure. That too will happen.

Looking back over the past couple of years, Apple can take pride in the fact that the iPhone challenged conventional wisdom of how consumers relate to their mobile phones, how content is consumed on the go and where the Internet is headed.

Above all, Apple CEO Steve Jobs and his team can take credit for the unrelenting focus on user-friendliness. The iPhone will have many competitors and copycats, but more touch screens and app stores won't substitute for what Apple knows best: the consumer.