APSs may be used to dynamically generate web pages. For instance, ASP can put random thoughts of the day on your home page, create a shopping cart for customers, or even link website content to your (ever changing) inventory. ASP pages tend to be easier to maintain than CGI scripts, due to their increased readability.
An ASP page is a web page with sever-side scripts embedded in the flow of HTML. Sever-side scripts are processed on the server, rather than on users' computers. The end result is an HTML page. The user never sees the scripts, but they'll be able to see their effects.
ASP scripts can be written in any language (perl, Visual C++, or C to name a few), but the most common combination is VBScript for server-side scripts, and Java Script for client-side scripts.