What To Expect From iPhone 6 (PHOTO)

The new iPhones have been on sale for less than a month but investors and fans alike are already looking ahead to next year's model: the iPhone6.

Largely because Apple makes major changes in its top-selling phone only every other year.

For 2013, the iPhone 5S stuck with the same screen and case design as the prior year's iPhone 5. Next year, however, will likely bring a whole new iPhone.

Apple did introduce two upgraded models in 2013, though the iPhone 5C was simply last year's model dressed up in a pretty plastic coating.

Apple said it sold 9 million iPhones in the first weekend of sales but has not released figures for the 5C alone. The 5S and 5C both have screens that measure four inches diagonally with a ratio of 1,136 by 640 pixels.