Active Server Pages (asp) is a Microsoft technology that allows even more flexibility. A Web page can contain Visual Basic code that the server executes when it lifts a page off the disk. This code can do just about anything -- read databases, run other programs, custom format pages based on the user's ID, etc. You have a great deal of flexibility. On the other hand, your Web pages now contain code that may have bugs in it, so it is possible for a page to "crash." With freedom comes responsibility...

Note that is now becoming common to see jsp and php extensions as well. Jsp is one of the latest additions to the Java Enterprise suite of APIs. "Jsp" stands for "Java Server Pages" and is effectively Java's response to ASP. The code embedded in a page is Java rather than Visual Basic. "Php" used to stand for "Personal Home Page," but now it's really just "PHP," which is a scripting language that's mostly used with Linux.)