What is the difference between Send and Sync?

Question

Accepted Answer

**Send** — can be transferred between threads. **Sync** — can be shared between threads.

**Send:**
- Type can be moved to another thread.
- Most types are Send.
- Rc is NOT Send.

**Sync:**
- Type can be referenced from multiple threads.
- &T is Sync if T is Sync.
- Cell is NOT Sync.

```rust
// Send
let data = vec![1, 2, 3];
std::thread::spawn(move || {
    println!("{:?}", data);
});

// Sync
use std::sync::Arc;
let data = Arc::new(vec![1, 2, 3]);
let data2 = Arc::clone(&data);
std::thread::spawn(move || println!("{:?}", data2));
std::thread::spawn(move || println!("{:?}", data));
```

**Key:** Send for moving, Sync for sharing.

Rust: What is the difference between Send and Sync?