What’s new? The iPhone 4 is thinner, with a clearer screen, improved camera and video capabilities and longer battery life.

How much thinner? It’s about three-eighths of an inch thick; the previous iPhone was nearly half an inch.

What’s different about the camera and video? It is getting a camera on the front that could be used for videoconferencing, in addition to a five-megapixel camera and a flash on the back. It can shoot high-definition video, catching up to some other smart phones.

How is the screen clearer? The display on the new iPhone remains 3.5 inches diagonally, but Jobs said it can show four times as many pixels — the individual colored dots that make up an image — as the previous screen.

How much more battery life? Improves to give up to seven hours of 3G talk.

When does it go on sale? June 24.

Cost? $199 for 16 gigabytes, $299 for 32 gigabytes

What about the iPhone 3GS? The iPhone 3GS, which debuted last year, still will be available, for $99.

Do customers still have to sign with AT&T? Yes, AT&T remains the exclusive U.S. carrier for the iPhone, and buyers will need to sign a two-year service contract.