Happy Birthday iPhone!

(NBC News) For many of us, life without a smartphone is hard to imagine.

That started ten years ago, when the very first iPhone went on sale.

More than a billion iPhone sales later, the device has changed the way we communicate.

By today's standards, that first iPhone was modest, only 4 gigabytes of storage, a camera that only took stills, and no apps.

More than three million iPhones sold that first year, and almost four times that many in 2008, when apps became available.

"That's affected not just smart phones, but the way business models have been created," notes CNET Senior Editor Scott Stein.

Another tipping point came when an HD video camera and Facetime were added in 2010.

"That opened the door as a communication and camera device where people started to pick up those phones as camera replacements," Stein says.

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