Michael Nitschinger's Blog: Understanding the Lithium Router - Part 1
In this article series we'll take an in-depth look at the Lithium router. This first part bootstraps your knowledge and lays a foundation for more advanced topics.
He introduces the Router component as having two purposes - matching a URL against the code to handle the request and the other is the reverse, creating URLs out of routes. He links to two pages where you can find more details on its API. He moves on to the request and response cycle the Router goes through each time a page is requested and walks you through some code to help it all make sense. There's also a bit at the end about creating URLs with the reverse routing methods.