Facebook Inc. (FB), the world’s biggest social-networking service, agreed to buy the Instagram mobile photo-sharing application for about $1 billion in cash and stock, its biggest acquisition yet. The transaction is expected to close later this quarter, Menlo Park, California-based Facebook said today in a statement on its site. The company plans to let Instagram remain independent from Facebook. “We need to be mindful about keeping and building on Instagram’s strengths and features rather than just trying to integrate everything into Facebook,” Facebook Chief Executive Officer Mark Zuckerberg said in a posting on ... (full story)