10.12Async Scope vs messaging

You may also hear Mule's:

Async scope

Conceptually:

main flow
   ↓
start work asynchronously
   ↓
main flow continues

But don't confuse that with durable messaging.

If you need:

guaranteed eventual processing
survival across application crash
redelivery
DLQ

a durable queue/message broker is usually a stronger architecture than merely launching asynchronous work in memory.