Instagram is a free application for iPhone, iPad or iTouch that allow the users to take pictures, retouch, apply filters and share in the social media websites like Facebook, Twitter or Flickr.
The main feature of Instagram is the retro look of the images that you get, similar to the effect of the Polaroid or Kodak Instamatic pictures.
Instagram has became a very popular application and by September 2011 they have more than 10 million registered users.