This document provides an overview of Mule ESB and messaging with Mule. It discusses: - Mule ESB 3.x, the Mule Management Console, and Mule Studio. - How Mule provides a messaging framework to transfer data between applications as messages with a payload, properties, and optional attachments. - The differences between Mule and a traditional ESB, with Mule only converting data as needed versus requiring an adapter for every application in a traditional ESB.