The Most Important Part Of The Next iPhone Announcement Won't Be The Next iPhone

It's all but confirmed that Apple will announce the next iPhone on September 10. And it's all but confirmed that most of the changes on that phone, which the press has dubbed the iPhone 5S, won't be on the outside.

It seems like Apple will continue its pattern of releasing an "S" model phone as it does every other year. The "S" models always look like the last model but have some internal improvements like a faster processor and better camera. Don't expect a radical new design or a larger screen.

But we already know what the biggest change will be. In a few weeks, all iPhones will get an operating system update called iOS 7. The new version is the most radical cosmetic change to iOS since the iPhone first launched six years ago.

While much of the talk on September 10 will be about what the iPhone 5S can do or how much the rumored "cheap" plastic iPhone will cost, iOS 7 is the bigger story. The millions and millions of people who already own an iPhone 4, 4S, or 5 will get the update for free.

iOS 7 was first introduced at Apple's developers conference in June. Since then, developers have been testing early versions of the software to make sure their apps are compatible when it launches. While the tech community is pretty familiar with what iOS 7 will be like, you can expect Apple to spend a lot of time going over the features again at the event on September 10. This will be the first time the general public gets a chance to look at the final version of the software, and Apple has to make sure they're ready for the sweeping changes that will take over all iPhones.

It's going to be jarring at first.

The new design in iOS 7 comes from Jony Ive, the executive who also designs hardware for Apple. All the basic icons have been redesigned with a more modern, "flatter" look. The apps themselves have new designs too. Everything feels lighter, with skinny fonts and fewer references to real-world objects. (For example, the Game Center app no longer looks like a green felt gaming table.)

The good news is, if you've had an iPhone for a while, Apple kept most stuff in the same place. The fonts and graphics may be unfamiliar, but everything is where you left it. (I've been testing early versions of iOS 7 since June, and I felt right at home within a day or so.) Think of iOS 7 as a fresh coat of paint for the iPhone.

Bottom line: This isn't the year for Apple lovers to obsess over hardware. It's another transition year, and it's all about the software and what's under the hood.