Who built it: Evan Spiegel, formerly of

Intuit,

and Bobby Murphy, previously of Revel Systems. Spiegel came up with the idea in a product design class at Stanford University. Snapchat’s office is located in Los Angeles.

Why it’s popular: The self-destruction feature encourages people to share fleeting moments without having to worry about storing files. It’s kind of secretive (though you can still take a screenshot of the image), and most importantly, it’s very fast.

Think of Snapchat as Instagram, but without performance anxiety. Snapchat takes “likes” and “shares” out of the equation, stripping the process down to something akin to basic one-to-one communication.

Not surprisingly, Snapchat is popular with a lot of younger smartphone users. According to a small study by Y Combinator partner Garry Tan, Snapchat is emerging as the app with the biggest usage difference between teens and young adults. About 13% of 13 to 18 year olds in the study use the app often, compared with 4% of 19 to 25 year olds.

Snapchat has been sitting on top of the App Store for the past month.

The phenomenon caught so quickly that

Facebook

ended up launching a similar self-destructing photo app called Poke. It didn’t catch on quite as well as Snapchat, however, and has fallen out of the top echelons of the App Store, according to AppData.

It’s rumored, according to several tech blogs, that Snapchat is raising additional funding from the backer of Instagram. That photo-sharing app sold for what was $1 billion at the time to Facebook.

The next time you see someone making funny faces to their smartphone, there’s a good chance they’re taking a photo with Snapchat for their friends. So, ask them what their Snapchat name is!