The question I've always had about Upworthy—the fastest-growing media startup in memory—is whether it had figured out how to exploit a single behavioral tic or created a system for finding and using those loopholes.
Because it was clear that they had figured out something, and that this something was powerful.
The social web is this strange, organic machine. People post stories on various domains, large and small. Small teams of people (social media editors) try to get momentum behind those stories on the sites of the big gatekeepers—Facebook, primarily, but also Twitter and Reddit. Then, if a story begins doing well by the efforts of the site that published or something else, the feedback loops kick in. Facebook, in particular, likes to add fuel to the fire, so a story that's got great initial sharing stats can go huge in a matter of minutes.
But what stories will have great stats? It's mostly guesswork, but some people are better than others at it, and Upworthy has been as good as they get.
The social terrain varies enormously and quickly. It depends on the psychology of different sets of millions of people of varying media sophistication and taste, not to mention the algorithms encoding the preferences of Facebook, et al. And the changes that come are as "viral" as the stories that pump through the networks. One day's hot way of doing something is tomorrow's tired cliche.