The next iPhone is set to be announced on September 10, if Internet rumors are any indication. If so, it will have been almost exactly 12 months between iPhone updates, setting up Apple up for a massive back-to-school and holiday push.

We won’t know exactly what CEO Tim Cook and his cadre of executives will announce until they take the stage. But between the rumors and what we already know about iOS 7, we can take some pretty good guesses.

Here are five things to expect from the new iPhone.

Welcome iPhone 5S And Little Sister 5C

Apple’s naming convention for the iPhone is fairly routine. One year it's a number (iPhone 3G, iPhone 4, iPhone 5), then next an “S” version (iPhone 3GS, iPhone 4S). This should be an “S” year.

Of course, Apple could throw a wrench in the plans by just calling it the “new” iPhone, the way it called both the third and fourth generation iPad the “new iPad” instead of the iPad 3 and iPad 4.

The iPhone 5S is likely to be the new flagship, the one that will sell for $199 on a two-year contract from the wireless carriers in the United States. But there might be a new entry into Apple’s iPhone series this time around with a budget device people have been calling the “iPhone 5C.” 

The iPhone 5C could have a plastic back and come in a variety of colors. Changing from the monochrome black and white of previous iPhone releases would be much like Apple did when it diversified its iPod lineup in the 2000s. it's reasonable to assume that the iPhone 5C might be $99 on a two-year contract from the carriers.

A Serious Print Job

Last year, Apple acquired a company called AuthenTec that makes chips for fingerprint sensors. These types of sensors can be used for biometric authentication—a way of using unique physical characteristics (such as fingerprints or retina patterns) for identification and other security purposes.

Apple is reportedly bringing a fingerprint sensor to the iPhone 5S. It would be situated on the familiar round “home” button of the phone, which may be convex, so a portion of it would be above the bezel/display of the phone. The home button would have a sapphire covering to help it stand the test of time. 

Why an iPhone fingerprint sensor? It could serve as the phone's default unlocking mechanism—and beyond. Apple could create a trusted mobile payments system like that of the Square Wallet, where you use your fingerprint to unlock your money when shopping. Or you could use your iPhone as a way to enter a building, such as your work or apartment.

That kind of sensor could just be a gimmick, much like Siri was initially thought to be. Or it could ultimately pioneer a new kind of must-have feature for portable devices. If Apple chooses to go that way, of course. (Among other things, fingerprint scanners have a number of known disadvantages, some of which become more serious the more widely the technology is used.)

The Interface Is Flat

In June, Apple announced iOS 7, the newest version of the operating system that runs both the iPhone and iPad. Mobile developers have been playing with it for the last couple months and Apple has released five different beta versions ahead of launch of the new iPhone.

The design of iOS 7 employs a concept called "flat design" that makes a distinct departure from what consumers are used to seeing on today's iPhones and iPads. Flat designs eschew the real-life characteristics of apps in favor of a simpler, more futuristic design concept. For instance, the bookshelves in the Newsstand app are gone in favor of a series of blue rows. The Notes app no longer looks like a yellow legal pad and now is a simple white on black design.

These changes permeate iOS 7. The font for most of the apps is now thinner and the buttons are now borderless. At the same time, the interface for iOS 7 hasn’t changed all that much. If you know how to use an iPhone or iPad right now, you will know how to get around with iOS 7. 

A Camera So Nice You'll Flash Twice

Rumors have popped up in the last week that the iPhone 5S will have dual LED flash for photos. According to reports, the different flashes will be white and a sort of off-yellow designed for taking “natural” looking pictures indoors. 

Rumors of hardware specifications are often hard to believe because they tend to range all over the board. But the iPhone 5S will likely see a camera of at least 8 megapixels and maybe more. For a point of comparison, Motorola’s new Moto X smartphone has a 10MP camera while the Samsung Galaxy S4 has a 13MP camera. The mother of all smartphone cameras resides in the Nokia Lumia 1020, weighing in at a whopping 41 megapixels.

Apple will also have four different camera modes in the iPhone 5S through iOS 7. There will be a “square” mode to take Instagram-like photos, a video mode, a panorama mode and the normal point-and-shoot mode. Users will be able to flick through modes on the camera with a side flick of the app.

A Smarter Siri

Apple’s virtual assistant is getting a beefy upgrade. It will be able to tap straight into a variety of additional databases including Wikipedia and Twitter. It will also use Microsoft’s Bing search engine to yield search results. Siri will have better, more relevant results for iPhone users and should be able to carry on better conversations within the app (as opposed to sending users to the Safari browser after a search query).

In addition, Siri will be able to control more aspects of the iPhone. You'll be able to tell Siri to return a phone call, control iTunes Radio or play a voicemail. And users will be able to choose whether Siri uses a male or female voice.

What are you looking forward to in the next iPhone? Let us know in the comments.