The System.Web.UI.Page class is associated with files that have an .aspx extension. These files are compiled at run time as System.Web.UI.Page objects and cached in server memory.

If you want to create a Web Forms page using the code-behind technique, derive from this class. Rapid application development (RAD) designers, such as Microsoft Visual Studio, automatically use this model to create Web Forms pages.

The System.Web.UI.Page object serves as the naming container for all server controls in a page, except those that implement the System.Web.UI.INamingContainer interface or are child controls of controls that implement this interface.

The System.Web.UI.Page class is a control that acts as the user interface for your Web application, and as such should be scrutinized to make sure best practices for writing secure code and securing applications are followed. For general information on these topics, see Overview of Web Application Security Threats, Security Policy Best Practices, and Key Security Concepts. For more specific information, see Securing Standard Controls, How to: Display Safe Error Messages, How to: Protect Against Script Exploits in a Web Application by Applying HTML Encoding to Strings, and Introduction to the Validation Controls.