Instagram hits 600 million monthly users, doubling the number in two years
Besides users, the number of advertisers is growing rapidly. Instagram ran its first ad three years ago, and already has 500,000 advertisers. It will generate $1.5 billion in ad revenue this year, rising to $5 billion by 2018 according to one estimate. Instagram's "Direct" messaging now has 300 million users, up nearly four times from the 80 million users of the feature that Instagram had last year.
Instagram has come a long way. Three months after launching on the App Store back in 2010, one million people were using the app. By April 2012, Facebook had agreed to pay $1 billion for Instagram. Soon, it became known as the place where you go to share pictures of your lunch. But CEO Kevin Systrom has much more in mind for the app. He sees Instagram becoming the place where users will be able to find a visual record of anything that went on in any part of the globe on any particular day.
source: Instagram via Forbes