> When you pass data to another thread, there are three options: 1) pass a copy, 2) hand off ownership to the other thread, and 3) transfer ownership to a mutex

> When you pass data to another thread, there are three options: 1) pass a copy, 2) hand off ownership to the other thread, and 3) transfer ownership to a mutex object, then borrow it from the mutex object as needed. All of these are memory and race condition safe due to compile time checking. There's more than those three: data can be shared via reference or reference counted pointers[Arc], which allows immutable access (more generally, concurrent access to any types for which this is safe, e.g. atomics and mutexes). A mutex is only necessary for mutating (nearly) arbitrary shared data. This is particularly powerful for literally zero-overhead read-only shared memory while still maintaining Rust's safety guarantees. [Arc]: http://doc.rust-lang.org/std/sync/struct.Arc.html http://doc.rust-lang.org/std/sync/struct.Arc.html