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 (2002) 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.
Pages can be generated by mixing server-side scripting code (including database access) with HTML and client-side code. For example:
\r\n<%if x=1 then%>\r\n X equals one\r\n<%else%>\r\n X is not one\r\n<%end if%>\r\n
This code results in the HTML
X equals onewhen the server-side variable X=1.
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.
In early 2002, standard 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 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, which can be viewed by any user.
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.