Active Server Pages (ASP) is Microsoft's server-side technology for dynamically-generated web pages that is marketed as an adjunct to Internet Information Server (IIS). ASP has gone through four major iterations, ASP 1.0 (distributed with IIS 3.0), ASP 2.0 (distributed with IIS 4.0), ASP 3.0 (distributed with IIS 5.0) and ASP.NET (part of the Microsoft .NET platform). The pre-.NET versions are currently referred to as "classic" ASP.
In the latest classic ASP, ASP 3.0, there are six built-in objectss that are available to the programmer, Application, ASPError, Request, Response, Server and Session. Each object corresponds to a group of frequently-used functionality useful for creating dynamic web pages.
\n<% If X=1 Then%>\n X equals one\n<% Else %>\n X is not one\n<% End If %>\n
The code between the <%...%> delimiters will be processed by the server. The resulting HTML is X equals one when the server-side variable X=1.
Most ASP pages are written in VBScript. Other scripting languages can be selected by using the @Language directive. JScript (Microsoft's implementation of JavaScript) is the other language that is usually available. PerlScript (Perl) and others are available as third-party add-ons.
Programming ASP websites is made easier by various built-in objects, such as a cookie-based session object that maintains variables from page to page.
Beginning in 2002, classic ASP is being replaced by ASP.NET, which among other things, allows the replacement of in-HTML scripting with full-fledged support for .NET languages such as Visual Basic .NET and C#. In-page scripting can still be used (and is fully supported), but now pages can use VS.NET and C# classes to generate pages instead of code in HTML pages.
According to news reports in 2002, the market share of ASP is in decline, with the free open source alternative PHP overtaking it in the server-side scripting market.
