In many ways, the rise of the open source web browser Firefox contradicts common wisdom and expectations. An industry with network effects, as is the case in the web browser industry, should follow the rationale of "the strong grows stronger, and the weak becomes weaker". This means that in the long run, a single dominant technology will prevail that prevents competing technologies from obtaining a foothold in the market. We can therefore explain the victory of Internet Explorer (IE) over Netscape mainly because IE was bundled with the Windows operating system; however, we still need to understand the rise of Firefox in a 'winner-takes-all market'. Could the characteristics of Firefox, an open source software web browser, explain this unexpected success? This book brings together insights from open source software, open standards, and standards-setting, and illustrates the dynamics of standards-settings by examining two standards battles: Internet Explorer versus Netscape, and Internet Explorer versus Firefox.