Instagram is a photo sharing application that is native to the iOS (iPhone, iPad, iPod touch). It is available for the version 3.1.2 and above. It has over 27 million users worldwide and is the most talked about mobile photo sharing app.
Instagram allows users to apply various photographic filters to the photos and post them on various social networking sites, including Facebook, Tumblr and Twitter, as well as its own. Instagram pictures must be square cropped. This is one distinctive feature that makes Instagram unique.
Event though Instagram is currently available in Apple app store it has announced that it would soon be available for Android phones too.
Instagram is a Free application