This document provides an overview of Mule ESB, including what it is, why it is used, its architecture and components. Mule ESB is an open-source enterprise service bus that allows for integration between applications. It provides endpoints, connectors, transformations and flow controls to route messages between systems. The document demonstrates Mule ESB's capabilities through Mule Studio, which is used to visually create and test integration flows, and the Mule Management Console for monitoring deployments.