US Patent 8700618 Tracking implicit trajectory of content sharing

A facility for tracking the sharing of distinguished content is described. When a user seeks to access the distinguished content from a client computer system using a URL associated with the distinguished content, the facility determines whether a user identifier is represented in the URL. If a user identifier is represented in the URL that is different from a user identifier that is persistently stored by the client computer system, the facility determines that the distinguished content has been shared with a user identified by the user identifier that is persistently stored by the client computer system by a user identified by the identifier represented in the URL.