Apple just announced the 4-Inch iPhone 5 at the Yerba Buena Center, in San Francisco. The handset looks great, and most of us are already in love with it. But what does the new screen size mean for App Store fans and developers? Read on and worry not, because we’ve explained everything.

Aspect ratio

For the first time since 2007 Apple has changed the aspect ratio of its iPhone, giving the sixth-gen handset a taller screen. The new iPhone 5 has a Retina display resolution of 326 p.p.i, but the handset’s taller, 4-inch screen means users can take advantage of more space: Calendar, for example, will show more events on the iPhone 5, and users can enjoy five rows of iOS apps rather than four on their Home screen. The iPhone 5′s screen resolution is 1,136 x 640, and Apple’s engineering team has built the handset’s touch sensors right into the smartphone’s display.

What this means for developers

The good news is that all iOS apps will work with the new iPhone in a kind of “compatibility mode.” But developers have the option of updating their applications to take advantage of this additional screen real estate. As Phil Schiller noted on stage moments ago:

We learned that they can update their apps quickly, and they want to do more with the display. Let me show you some examples. All your software works just like before. But we have given some devs early access.

[Developing...]

Remember, you can keep up to date with news from the iPhone event as it happens by heading over to the AppAdvice live blog.