Fire-and-forget information exchange. Participants in an asynchronous messaging system don't have to wait for a response from the recipient, because they can rely on the messaging infrastructure to ensure delivery. This is a vital ingredient in loosely coupled systems such as web services, because it allows participants to communicate reliably even if one of the parties is temporarily offline, busy, or unobtainable. Asynchronous messaging systems are also vastly more scalable than those that rely on direct connections, such as remote procedure calls (RPCs).