Explain async/await in Rust and how it differs from other languages.

Async/await in Rust: Zero-cost futures, cooperative multitasking, no built-in runtime, compile-time transformation, Pin for self-referential types. Key concepts: Future trait, executors drive futures, async fn returns impl Future, .await suspends execution. Differences from other languages: No built-in runtime, zero allocation for simple futures, compile-time async transformation, explicit executor choice.