In Web site development with
ASP.NET, the
Content Page is a page that is associated to a
Master Page. A Content Page will contain only markup and controls inside
Content controls and it cannot have any top-level content of its own. Any
Content Page can use controls that specifically override content placeholder
sections in the Master Page.
See ASP.NET
See also "Customizing
and Managing Your Site's Appearance" on
Webreference.com.