How can we better understand how content circulates within contemporary networked culture? The collective decisions people make about whether to pass along content are profoundly reshaping the media landscape. Many content creators struggle with the growing prominence of grassroots audience practices, while an array of online communication tools have arisen to facilitate informal, instantaneous sharing. This environment offers new opportunities for people to pass along content and new models to generate revenue from user activities. While the means for people to circulate material have proliferated, recommending and sharing are impulses that have long driven how people interact around media texts. We'll focus on the social logics and cultural practices that have enabled and popularized these new platforms, explaining why (not just how) sharing has become common practice.