Ode To The Code has a very in depth article that goes to the guts of Master Pages, one of the new features of ASP.Net 2.0, showing some implementation details and clearing some common misconceptions.
The conclusion is quite simple, while being perfect for designing the common sections of a web page to be used across a web site, Master Pages shouldn’t be treated as a base page that other pages can extend ( just like an abstract class), instead they should be seen as a control that will be placed inside the page.
ASP.Net 2.0 – Master Pages: Tips, Tricks, and Traps
internet