Master Pages are used to provide the consistent layout and common behavior for multiple pages in your applications.then u can add the Contenetplaceholder to add child pages custom content. User Controls: Sometimes u need the functionality in your web pages which is not possible using the Built-In Web server controls then user can create his own controls called user controls using asp.net builtin controls.User controls are those with .aspx extensions and u can share it in the application.

Master Pages are used to provide the consistent layout and common behavior for multiple pages in your applications.then u can add the Contenetplaceholder to add child pages custom content. User Controls: Sometimes u need the functionality in your web pages which is not possible using the Built-In Web server controls then user can create his own controls called user controls using asp.net builtin controls.User controls are those with .aspx extensions and u can share it in the application.