The home screen has always been at the center of the iPhone experience. At WWDC, Apple signaled that we're moving on.

With iOS 9, the bulk of interaction will happen elsewhere, dispersed among intelligent notification panels, powerful search tools, and context-specific suggestions that put relevant apps a flick away. The dependable home screen will still exist, but for the first time, it feels secondary. These days, the smartphone experience is just too fast and fluid to be pinned to a grid.

From birth, the home screen was the iPhone's face to the world. It was the first thing that popped up when Steve Jobs swiped his finger across the first iPhone's lock screen on stage in 2007. Looking back at that event, it's remarkable how little has changed. Today's home screen has more real estate and less gloss, but beyond that, the two are identical.

In the early days, the home screen was crucial to the iPhone's appeal. For a gadget that was many gadgets in one—a phone, an iPod, and an Internet communicator, not to mention a camera, a map, and more—the orderly grid of icons organized functionality in a perfectly uncomplicated way. To someone coming from a PC, the home screen was the desktop and Start button all in one. It was so important that it got its own dedicated button. No matter what you were doing on your phone, if you pressed the thumb-sized disc below the screen, you were safely shuttled home.