Free Software has lived in obscurity for many years, being known only by academics and hobbyists. But in the last few years, Free Software and Open Source (a related concept) have attracted the attention of both large companies and ordninary users, and moved into the mainstream in the form of projects such as Linux and the Apache web server. We will give a brief overview of the history of Free Software and Open Source, discuss the underlying philosophies and the difference between them, and have a look at why Free Software and Open Source can be beneficial for both users and developers. We will also briefly discuss the "Bazaar" development style commonly associated with Open Source, and how this differs from the traditional approach.