Dynamic Web Pages are pages that are generated, rather than hand-written. This is usually acomplished by a Web Scripting language, most commonly CGI or PHP. This technology allows pages to contain content that changes depending on a users interaction with the site.

An Example
A catalogue of products contains many thousands of entries, which would take a long time to write individual pages for. It would be even harder to ensure that the prices stayed up to date. It is much easier, and more efficient, to create a product database, and link it directly to your site. Rather than write many product pages, you write one "Template" page, which dynamically changes its content depending on the product requested; and, because its pulled from a database, you can be sure that the product does not have an out-of-date price.

All of these technologies require support by the Web Server to work correctly. The most commonly supported technologies are:

Frontpage Extensions
Frontpage Extensions are a technology developed by Microsoft to allow Frontpage users to include dynamic elements in their Websites e.g. Counters, Forms, Roll-over images, etc. Frontpage itself takes care of the scripting side of things, based upon your selections. This is a great technique for beginners, as it is very simple to use. However, its limitations are quickly reached by the Power User.

Common Gateway Interface (CGI)
CGI is a specification that allows Web Pages to communicate with a CGI program. A CGI program commonly accepts input from the user, and returns a page dynamically created depending on the users input. The program can be written in almost any language, including Perl, C, or Java. Common uses for this include FormMail (a free feedback form processor). This is a very powerful technology, but is quickly being replaced in many applications by PHP.

PHP: Hypertext Preprocessor (PHP)
The most modern of the technologies, PHP is an inline scripting language that allows the developer to embed script directly into a web page. The dynamic parts of a page are generated as the page loads. It also interfaces well with popular Database clients, for example MySQL, to create database-driven web content. The Lawyers Online website (i.e. the pages you are currently reading) is written using PHP.