From this NYT look at the evolving Buzzfeed:
As the consumer Web has matured, readers have become minipublishers, using social media platforms to share information they think will entertain and enlighten their friends. No longer is it just about so-called sticky content that keeps readers around, or even clicky content that causes them to hit a link; it’s also about serving up content that is spreadable.
Hit the right note, and your readers become like bees, stopping by your site to grab links and heading back out on the Web to pollinate other platforms. That behavior has tapped into something visceral, a kind of game in which the person finding something delicious gains social capital for sharing it.