Site routing lets you handle what happens when a user enters a specific address in your domain. Site routing can use URL's that are not directly connected to a page file.
A good case for example is if you have an info page whose address is mydomain.com/info and you also want anyone who enters the address mydomain.com/about to get to your info page.
You can use routing to do this.
Routing also lets you redirect users using an HTML redirect code and permanent redirect code to either a page on your site, a path in your domain or a URL.