An object (e.g., a video, a widget, etc.) may carry generation information, indicating the length of the referral chain that led to the object's being downloaded. Some users become aware of the object through initial publicity. When these users download an instance of the object, that instance is a generation zero instance. The object may contain a mechanism (e.g., a link) that invites other users to download an instance of the objects. When a user follows such a link and downloads an instance of the object, the downloaded instance has a higher generation than the instance that presented the link to the user. For example, if a generation zero object refers a download, then the downloaded object instance may have generation one. Generation information may be collected and analyzed to determine how successfully an object propagates.