In the previous video we left the question as to how N.V.C.

associated the URL comic books/detail with our controller action unanswered.

Let's answer that question now.

In the URL http://teamtreehouse.com/,

http is the protocol, and teamtreehouse.com is the host name.

Typically, the host name is the domain name of the website.

However, when running websites locally, a special name, localhost is used.

The number following the colon, after the host name,

is our port number, which in my case is 50153.

Your port number might be different as Visual Studio assigns a random

number when creating ASP.NET projects.

Using a different explicit port number for each project allows each to be run locally

at the same even though they're all using the same host name local host.

If the terms URL, Protocol, Host Name or

Port are unfamiliar to you, check the teachers notes for

links to resources that will explain these concepts in detail.

The URL, http://localhost:50153/

would display the default page for our website.

Often this page is referred to as the Home Page.

For the URL, http://localhost:50153/ComicBooks/Detail,

everything to the right of the port number is known as the Path.

So while the combination of the host name and the port number

is used to determine which website the request is intended for, the path is used

to determine which resource within that website is being requested.

Whenever NVC processes the request, it uses simple pattern matching

against the path to determine the name of the controller and

action that should be used in the form of controller/action.

So the URL path, ComicBooks/Detail would map to a controller

named ComicBooks and an action method named Detail.

The process of matching a URL to a controller action is called url routing.

URL routing is not unique to Asp.netnvc.

Many other web frameworks, both server side and

client side, use the concept of URL routing.

Let's take a closer look at why we're getting an error

when requesting our website's home page.

When making a request, I'll supply in a path,

NVC will default the controller name to home and the action name to index.

We're getting a 404 error because our project doesn't contain a controller

named home controller, let alone a method on that controller named index.

If we were to request the URL path comic books, NVC would successfully find

our comic books controller but we'd still get a 404 error because our

controller currently doesn't contain an action method named index.

In a later video,

we'll add the index action method which will display a list of comic books.

We're just scratching the surface of what URL routing is capable of.

But for now, these basic concepts are just what we need to know

in order to continue building out our website.

Our controller's detail action method currently just returns a string literal.

Let's see if we can improve upon that design in the next video.