What is the role of the AEM Dispatcher?

The dispatcher is AEM’s caching and/or load balancing tool. By using the dispatcher it can also help protect your AEM server from attack since it will be using cached pages. The goal of the dispatcher is to cache as much content as possible, so it does not need to access the layout engine. Load balancing is the practice of distributing computational load of the website across several instances of AEM. The benefits of using the dispatcher as a load balancing tool is so that you gain increased processing power since the dispatcher shares document requests between several instances of AEM, and to have increased fail-safe coverage. This is accomplished by if the dispatcher does not receive responses from an instance, it will automatically relay the request to another instance.