Taken from http://www.linuxforum.com/lamp-manual.php
"What is LAMP?
LAMP is an open source webserver solution which is both powerful and stable.
LAMP stands for Linux, Apache, MySQL, and PHP. This combination of software allows one to build and customize a high performance and cutting edge webserver. All that is required is a decent computer (See the FAQ for hardware requirements) and a willingness to learn.
Linux is an open source and constantly evolving operating system which allows the administrator full control over almost every system aspect. In recent years, Linux has proven itself to be a production level competitor in the OS world. Popular choices for the Linux distribution are Red Hat, Debian, and Slackware.
Apache 1.3.x, a powerful and well documented webserver application, handles the actual web page serving. Everything you see in your web browser came from the Apache webserver. Although Apache 2.0 is available for use, Apache 1.3.x is still the standard for LAMP servers. With internals that have been tested and perfected, Apache 1.3.x proves to be the best WWW server available today.
MySQL is a database server that holds content for many things. For example, one could store website member information in a MySQL database for use on a website. A database server allows a webmaster to keep data organized and accessible. Database driven websites are now becoming more prevalent as users demand dynamic and customizable websites. The most popular open source database server is of course, MySQL.
PHP is a relatively new server side programming language which allows webmasters to easily add dynamic pages to their website. PHP is extremely versatile, as it can do everything from printing database data to a webpage to declaring browser cookies. Bear in mind all of these applications are open source and free for your use- you are free to experiment and modify."