Within one week of its launch in October, photo sharing app Instagram had 100,000 signups. Seven months later, it had 4.25 million users.
Online photo sharing has long-been popular: Picasa launched in 2002; Flickr was founded in 2004, and Facebook was home to about 60 billion photos by the end of 2010. But mobile applications have suddenly exploded in popularity. Photo shooting and editing apps like Hipstamatic, Darkroom and CameraBag have been downloaded to millions of smartphones in the the past couple of years.
So many photo apps have launched, in fact, that the online photo editing site Aviary released a photo API this month to help people build photo apps.The API allows developers to automatically apply filters, effects, watermarks and other edits to photos, all in the cloud. The trend is clear: Millions of people are getting their hands on phones with cameras, and developers are taking advantage of it.
If photo sharing has been around for so long already, including mobile versions of Facebook and Flickr, what's made mobile apps like Hipstamatic and Instagram so wildly popular?
1. Phone Cameras No Longer Suck
