Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Instagram is a free iPhone photo sharing application that allows users to take photos, apply a filter, enhance it with many different possible effects and share it on the service or a variety of other social networking services, including Facebook, Twitter, Tumblr, Flickr and others. Recently, the common photo sharing app turned in the most downloaded and famous mobile application worldwide, after it was acquired by Facebook network for $1 billion. To find out more about the Instagram app read this book.