It's no secret--Snapchat is not very intuitive.

And that's by design, argues Josh Elman, partner at venture capital firm Greylock Partners and former product manager at Twitter and LinkedIn.

The Snapchat app uses a principle Elman refers to in a new blog post as "shareable design": the idea that an interface is best understood when explained by someone else. That type of design often is best applied to social-media platforms, and even more so ones used largely by teens. It's pretty likely that, in the course of using a new app, a
16-year-old is going to show it off to his or her friend. That interaction adds value for both the newbie, who gains knowledge about the app, and the explainer, who feels the joy of teaching someone something they didn't know.

And, of course, it adds value for Snapchat, which just got two people to share a memorable experience involving its app.

"It's converting you into an evangelist for its product," Elman writes, "and you don't even feel like you're evangelizing: You're just showing your friends how to do something neat."

Using many of Snapchat's most fun features requires some knowledge that can't be gained by just glancing at the screen: Press and hold to summon the facial recognition feature; swipe down to see who has recently added you as a friend. No onscreen instructions or explanatory menu bar let you know to do this.

"Each of those seemingly obscure features," Elman notes, "is an opportunity for its users to show their friends how to do something cool."

If you get a photo of your friend's face mashed-up with a pig's, it's likely you'll ask him or her how it was done.

Surely, the design is also partly out of necessity. A Microsoft Word-style toolbar isn't going to work on a five-inch screen--especially when you need most of the screen to take, view, and edit a photo. Features like swiping or pressing-and-holding require no real estate at all.

But hiding new features, and making people discover them socially, is a clever strategy for getting people to talk about your product.

Elman points out this kind of design will soon come to replace the more intuitive interfaces that, with the onset of personal computers, dominated the 80s and 90s. Wearables rarely have enough real estate for instructions, after all, and augmented reality would lose much of its luster if a menu floated right in front of you.