A Photo App or 11 Buildings

In many ways, 2012 was the year of the "B" word: billion. Few milestones in business are as significant as hitting a billion, and this year it defined some of the biggest moments in technology.

For Silicon Valley, it marked a return to a headier time, reminiscent of the eye-popping figures for everything from acquisitions to IPOs during the boom over a decade ago.

Whether it was a billion dollars for a tiny startup with no revenue (hello, Instagram), a billion friends for a company that made enemies with its IPO (we see you, Facebook), or a patent ruling worth a billion bucks (enjoy, Apple), the threshold for serious deal-making and score-settling was sky-high in 2012.