PawPub has five fundamental types of “pushable object” (anything that can be pushed to another instance), which are:

• Actor: represents an entity that can “do something”, e.g. a user
• Note: represents a post, article or message of some kind
• Interaction: represents an action that can be taken on a note (e.g. like/dislike)
• Extension: represents an arbitrary, extension-defined object
• Tombstone: represents an object that previously existed but has been deleted