title: Does Rust automatically execute code using multithreads
body: <p>I am reading about <a href="https://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html" rel="nofollow noreferrer">Rust's ownership</a> and it turns out that Rust's ownership, reference, and borrow features focus on preventing data race via some restrictions in reference mutability.</p>
  <p>I wonder why Rust forces us to obey these restrictions? Is that true that Rust will execute my code automatically in multithreaded mode? Otherwise, why do I have to care about the restrictions even if my code only executes in single-threaded mode by default?</p>