ASP.NET MVC User routing like that in StackOverflow?

Question

I\'ve looked at the routing on StackOverflow and I\'ve got a very noobie question, but something I\'d like clarification none the less.

I\'m looking specifically at

Answer 1

Probably just uses a specific route to handle it, also using a regex to specify the format of the ID (so it doesn't get confused with other routes that would contain action names in that position).

// one route for details
routes.MapRoute("UserProfile",
     "Users/{id}/{slug}",
     new { controller = "Users", action = "Details", slug = string.Empty },
     new { id = @"\d+" }
);
// one route for everything else
routes.MapRoute("Default",
     "{controller}/{action}/{id}",
     new { controller = "Home", action = "Index", id = UrlParameter.Optional}
);