An Actor is an addressable entity in ActivityPub — a user account, a bot, a service, or any other thing that can send and receive activities. Each actor has an inbox (where it receives activities from the federation) and an outbox (where it publishes activities).
Actors are identified by URLs and discoverable via WebFinger. The protocol makes no distinction between an actor on a single-person instance and an actor on a server with millions of users — a design choice that preserves formal equality but doesn’t address the power asymmetries between volunteer-run instances and corporate-scale deployments. This is one of the points where the standardization process bracketed political questions as “out of scope”: the specification treats all actors as equivalent nodes, regardless of the resources and governance behind them.
Related terms
- Activity — the actions that actors perform
- Federation — the network of servers hosting actors