Active Server Pages (ASP) is a server-side scripting environment that you can use to create and run dynamic, interactive Web server applications. With ASP, you can combine HTML pages, script commands, and COM components to create interactive Web pages or powerful Web-based applications, which are easy to develop and modify.

If you are an HTML author, you will find that server-side scripts written in ASP are an easy way to begin creating more complex, real-world Web applications. If you have ever wanted to store HTML form information in a database, personalize Web sites according to visitor preferences, or use different HTML features based on the browser, you will find that ASP provides a compelling solution. For example, previously, to process user input on the Web server you would have had to learn a language such as Perl or C to build a conventional Common Gateway Interface (CGI) application.

With ASP, however, you can collect HTML form information and pass it to a database using simple server-side scripts embedded directly in your HTML documents. If you are already familiar with scripting languages such as VBScript or JScript (JScript is the Microsoft implementation of the ECMA 262 language specification), you will have little trouble learning ASP.

Since ASP is designed to be language-neutral, if you are skilled at a scripting language such as VBScript, JavaScript, or PERL, you already know how to use Active Server Pages. What more, in your ASP pages you can use any scripting language for which you have installed a COM compliant scripting engine. ASP comes with VBScript and JavaScript scripting engines, but you can also install scripting engines for PERL, REXX, and Python, which are available through third-party vendors.

If you develop back-end Web applications in a programming language, such as Visual Basic, C++, or Java, you will find ASP a flexible way to quickly create Web applications. Besides adding scripts to create an engaging HTML interface for your application, you can build your own COM components. You can encapsulate your application's business logic into reusable modules that you can call from a script, from another component, or from another program.

A server-side script begins to run when a browser requests an .asp file from your Web server. Your Web server then calls ASP, which processes the requested file from top to bottom, executes any script commands, and sends a Web page to the browser.

Because your scripts run on the server rather than on the client, your Web server does all the work involved in generating the HTML pages sent to browsers. Server-side scripts cannot be readily copied because only the result of the script is returned to the browser. Users cannot view the script commands that created the page they are viewing.

Many people forget that ASP isn't just for making dynamic HTML pages. ASP can be used to create pages of all kinds, or even binary data, like images. Some examples have used XML, audio play lists, text files, GIFs, and JPEGs - literally anything with a MIME type that he browser recognizes.

The code needed to make this happen is really quite simple. It takes only one line to change the HTTP header to produce a different MIME type, and thus force the web browser to interpret the file differently. One application for this ability is to create a style sheet using ASP.