Well, Erlang-like actor model is one basic pattern for achieving safe concurrency. A second one is keeping data read-only so that it can be freely accessed by multiple threads; and a further pattern is serializing access at run time (either using explicit locks, or in special cases with "non-blocking" algorithms and data structures). Rust is pretty unique in being able to comfortably encompass all of these patterns in its concurrency model, while ensuring safety.