It's likely that you've started to hear people talk a lot about Instagram, or what has now become known as the "billion-dollar app." Yes, back in April Facebook purchased Instagram for $1 billion. So what is so special about the app and how did it become so very popular?
As explained in the Qwiki above, the app was first released for the iPhone in 2010. And it was simple to use - launch the app, which launches the camera, take a photo and apply a cool filter or effect to the photo. Here's one example of a photo I took on Instagram. As you can see, it gave everyone with an iPhone the tools to be a creative photographer. Naturally, the app also has some cool sharing functions - you can follow users and comment and "like" their photos.
But something else big happened that month - Facebook decided to buy Instagram for a whole lot of cash. Facebook CEO Mark Zuckerberg promised in his announcement of the acquisition that it would let Instagram stand on its own. However, not everyone believed that. The Instagram faithful worried that Facebook would change the app for the worse.