This document discusses the psychology and motivations behind sharing content online. It identifies several "personas of sharers", including altruists who share to help others, careerists who share work-related content, hipsters who see sharing as part of their identity, boomerangs who seek engagement through provocative posts, connectors who share to foster relationships, and selectives who only share what they think will be relevant to the recipient. The document also provides credits for the sources of images and studies referenced.