ASP.NET
While goining through code,saw this interesting stuff..basically used to specify the typename of a base class and its associated code-behind class. Check this on MSDN
With the introduction of Master pages in 2.0, we can now design the page which contains contents repeated on each page -like menus, navigation, logos. We can also combine the functionality used by all web pages at single place and derive all our pages from this master page... Here is an excellent article on master pages by Scott Allen - providing tips,tricks and traps. Microsoft also provided 4 design templates based on the category. You can find them here...