a ASP.NET control that defines a relative region for content in a master page, and renders all text, markup, and server controls from a related Content control found in a content page.
A ContentPlaceHolder control defines a relative region for content in a master page, and renders all text, markup, and server controls from a related Content control found in a content page.
A Content control is associated with a ContentPlaceHolder using its ContentPlaceHolderID property. Set the ContentPlaceHolderID property to the value of the ID property of the related ContentPlaceHolder control in a master page. More than one ContentPlaceHolder can be declared in a master page.
Within a content page, only one Content control can supply the content for a ContentPlaceHolder in the master page. However, in each content page that uses a master page, you can have separate Content controls associated with the ContentPlaceHolder. For example, you can define the ContentPlaceHolder for the page title in a master page. For each content page that uses the master page, you can add a Content control that supplies the text and markup for the page title.
