Active Server Pages (ASP) is Microsoft’s server-side script engine for dynamically-generated web pages. It is marketed as an add-on to Internet Information Services (IIS). Programming ASP websites is made easier by various built-in objects. Each object corresponds to a group of frequently-used functionality useful for creating dynamic web pages. In ASP 2.0 there are six such built-in objects: Application, ASPError, Request, Response, Server, and Session. Session, for example, is a cookie-based session object that maintains variables from page to page.

Most ASP pages are written in VBScript, but any other Active Scripting engine can be selected instead by using the @Language directive or the <script language=”language” runat=”server”> syntax.
JScript (Microsoft’s implementation of ECMAScript) is the other language that is usually available.
PerlScript (a derivative of Perl) and others are available as third-party installable Active Scripting engines.

InstantASP and ChiliASP are technologies that run ASP without Windows Operating System. There are large open source communities on the WWW, such as ASPNuke, which produce ASP scripts, components and applications to be used for free under certain license terms.