In Web site development with
ASP.NET, the master page
is a feature that enables you to define common structure and interface markup
elements for your
Web site, including
headers,
footers, style
definitions, or navigation bars. The master page can be shared by any of the
pages in your Web site, called the
Content Page,
and removes need to duplicate code for shared elements within your Web site.
See ASP.NET
See also "Customizing
and Managing Your Site's Appearance" on
Webreference.com.