Facebook announced Monday that it made a billion-dollar-deal to buy the startup behind wildly popular smartphone photo sharing application Instagram. \"For years, we\'ve focused on building the best experience for sharing photos with your friends and family,\" Facebook co-founder Mark Zuckerberg said in announcing the deal. \"Now, we\'ll be able to work even more closely with the Instagram team to also offer the best experiences for sharing beautiful mobile photos with people based on your interests.\" Zuckerberg called the acquisition \"an important milestone for Facebook because it\'s the first time we\'ve ever acquired a product and company with so many users. We don\'t plan on doing many more of these, if any at all. \"But providing the best photo sharing experience is one reason why so many people love Facebook and we knew it would be worth bringing these two companies together.\" An Instagram application tuned to Apple\'s iPhones, iPads, and iPod touch devices has been downloaded more than 27 million times since the first version was released in late 2010 by the San Francisco startup. Instagram co-founder Kevin Systrom released the figure while providing a glimpse last month at a version of the application tailored for smartphones power by Google-backed Android software. The free mini-program lets people give classic looks to square photos using \"filters\" and then share them at Twitter, Facebook or other social networks. Apple crowned Instagram its app-of-the-year for 2011. \"We\'re psyched to be joining Facebook,\" Systrom said in a blog post Monday at the Instagram website. \"It\'s important to be clear that Instagram is not going away,\" he continued. \"We\'ll be working with Facebook to evolve Instagram and build the network.\" Instagram\'s roster of backers includes Twitter co-founder Jack Dorsey. Facebook in February filed for a stock offering and could raise as much as $10 billion in the largest flotation ever by an Internet company on Wall Street. Facebook -- the leading social network in all but six countries, notably China and Russia -- said it has more than 845 million users, including 483 million who log in daily. Facebook\'s value has been estimated at between $75 billion and $100 billion.