ASP.NET, first released in January 2002, has superseded ASP.
Initially released as an add-on to Internet Information Services (IIS) via the Windows NT 4.0 Option Pack (ca. 1996), it is included as a free component of Windows Server (since the initial release of Windows 2000 Server). There have been three versions of ASP, each introduced with different versions of IIS:
ASP 2.0 provides six built-in objects: Application, ASPError, Request, Response, Server, and Session.
Session object, for example, represents a session that maintains the state of variables from page to page. The Active Scripting engine's support of the Component Object Model (COM) enables ASP websites to access functionality in compiled libraries such as DLLs.
ASP 3.0 does not differ greatly from ASP 2.0 but it does offer some additional enhancements such as Server.Transfer method, Server.Execute method, and an enhanced ASPError object. ASP 3.0 also enables buffering by default and optimized the engine for better performance.