AEM Dispatcher :
The Dispatcher is Adobe Experience Manager's caching and/or load balancing tool that helps realize a fast and dynamic Web authoring environment.
In a load balancing role, the Dispatcher distributes user requests (load) across different AEM instances (renders).
For caching, the Dispatcher works as part of an HTTP server, such as Apache, with the aim of storing (or "caching") as much of the static website content as possible and accessing the website's layout engine as infrequently as possible.
For caching, the Dispatcher module uses the Web server's ability to serve static content. The Dispatcher places the cached documents in the document root of the Web server.
1. The Dispatcher uses the web server's ability to serve static content. The Dispatcher stores cached documents in the web server’s document root. The Dispatcher has two primary methods for updating the cache content when changes are made to the website.
2. Content Updates remove the pages that have changed, as well as files that are directly associated with them.
Auto-Invalidation automatically invalidates those parts of the cache that may be out of date after an update. For example, it effectively flags relevant pages as being out of date, without deleting anything.