Abstract: A method, apparatus, system, and computer program product provides the ability to track user interaction with content. An interaction with content by a user is recognized. Data related to the interaction is communicated, in a first engagement message, to a publishing service application. The data includes an identity of the user, an identity of the content interacted with, an engagement type, and an identity of the previous user who directly influenced the interaction. The publishing service determines a likelihood that the interaction will cause other users to further interact with the content. Upon a positive determination that the interaction will cause other users to further interact with the content, the determination is communicated to a viral influence application for further processing.