actor model concept
Each actor owns its own state, exposed only through messages.
Each actor owns its own state, exposed only through messages. No shared memory. Sending a message is asynchronous; receiving is sequential per actor. Eliminates classes of concurrency bugs (no locks, no shared mutable state) at the cost of new ones (mailbox overflows, ordering surprises across actors). Erlang's process model and Akka's actors are the canonical implementations; Go's goroutines + channels lean adjacent.