Hi,
suhasakole:
we have an usercontrol in .net 1.0,1.1 why microsoft implimented the masterpage concept in 2.0
as work done by master page is same as usercontrol do
In fact, the master page drives from the user control. When the aoolication executs the master page just like a usercontrol on the content page.
You’ll only need to write the common pieces once - in the master page. A master page can serve as a template for one or more web forms. Each ASPX web form only needs to define the content unique to itself, and this content will plug into specified areas of the master page layout.
The more about how the master page works you can try to refer this greate artcile: http://www.odetocode.com/Articles/450.aspx
About how to use master page to building a professional web application with a consistent, easy to maintain layout in ASP.NET, you can try to refer this article: http://www.odetocode.com/Articles/419.aspx.