Happy birthday Instagram! Though the photo-sharing site wasn’t made available to the public until October 2010, the first Instagram image was taken two years ago when the app went by the codename, erm, Codename. 

The photo is of a rather cute looking puppy sitting next to a sandaled foot. This was the first of more than one billion photos that have been shot using Instagram, with the site boasting over 50 million users across the globe.

Available as a mobile app, Instagram enables users to shoot photographs with their camera phones before sharing them on social networks including Facebook and Twitter. Various filters can be applied to the images to give them a retro feel. 

In April 2012, Facebook founder and CEO, Mark Zuckerberg made an offer to buy Instagram for a whopping $1 billion, though the deal is still waiting to be approved. 

Not bad for a photo-sharing site that began with a picture of a dog and a foot in a flip-flop.

Tell us why you use Instagram? Tell us why you don't. All in the comments below please.