LAMP stands for Linux, Apache, MySQL and PHP / Perl / Python, which is by far the most popular combination of web technologies.
DreamHost specializes in LAMP (using Debian) hosting, not only because they are popular, but also because they are well documented around the Web, seasoned in security and sophisticated in features. They are free and one can easily find plenty of useful articles to learn more about them, thus more quickly becoming adept in using DreamHost service.