What Happens if routing is not there in MVC ?

You can also check below urls

http://msdn.microsoft.com/en-us/library/vstudio/cc668201(v=vs.100).aspx
http://www.asp.net/mvc/tutorials/older-versions/controllers-and-routing/asp-net-mvc-routing-overview-cs
http://www.codeproject.com/Tips/573454/Routing-in-MVC
http://www.dotnet-tricks.com/Tutorial/mvc/HXHK010113-Routing-in-Asp.Net-MVC-with-example.html

hope will be helpful to you

Read this :
http://www.c-sharpcorner.com/UploadFile/56fb14/working-with-routes-in-mvc-framework/

Hope will help.

Routing provides a special inbuilt feature of URL rewriting.You can achieve this using routing.Moreover, it would be very helpful if you are creating single page applications as well.
We used to achieve URL rewriting in Asp.Net with rules,all that stuff is bypassed in MVC.

Learn Routing from here

 
http://www.codeproject.com/Tips/573454/Routing-in-MVC
http://www.asp.net/mvc/tutorials/older-versions/controllers-and-routing/asp-net-mvc-routing-overview-cs