The cash and stock deal is the biggest to date for the social network colossus, and gives it one of the most popular smartphone photo sharing apps. After just two years, Instagram has about 30M users, almost all on iPhones — the company introduced a version for Android phones last week. The application gives users the ability to create special effects with the photos they take on their smartphones, and share the end result with others on Facebook. CEO Mark Zuckerberg said on his Facebook site that he’s “committed to building and growing Instagram independently. Millions of people around the world love the Instagram app and the brand associated with it, and our goal is to help spread this app and brand to even more people.” Facebook announced the deal as it prepares to go public with a stock offering expected to raise $10B.