What’s So Good About Master Pages in Microsoft ASP.NET
Master pages in ASP.NET a powerful feature which allows developers to create template-like pages which contain information that is common to all pages in a site or all pages in one section of a site such as corporate logo, company information, headers, footers and navigation links. Content pages can then be created which are based on the master page(s). Master pages use the file extension “.master” which is automatically protected by the server and cannot therefore be downloaded by clients.