[MatthewRayfield]

It's a succinct way of describing your product.

From http://ycombinator.com/howtoapply.html :

One good trick for describing a project concisely is to explain it as a variant of something the audience already knows. It's like Wikipedia, but within an organization. It's like an answering service, but for email. It's eBay for jobs. This form of description is wonderfully efficient. Don't worry that it will make your idea seem "derivative." Some of the best ideas in history began by sticking together two existing ideas no one realized could be combined.