This is a comparatively long chapter in which we discussed message channel patterns, different types of channels, and the default implementations of channels provided by Spring. We also covered load balancing, failover, error handling on message channels, persisting messages, and adding interceptors. All these concepts are at the core of building a reliable and scalable solution, and we will see its hands-on implementation in the upcoming chapters where we will discuss Spring Integration components such as service activators, gateway, delayers, and so on that are used to process messages.