Firefox is the open-source web browser built by Mozilla, the project that grew out of Netscape’s 1998 source code release. The Mozilla Foundation announced the worldwide availability of Firefox 1.0 on November 9, 2004, describing it as the product of “a desire for a more robust, user-friendly and trustworthy web experience.”
The 1.0 release leaned on practical, user-facing features rather than raw novelty. Mozilla’s press release highlighted an integrated pop-up blocker that “lets users — not websites — decide when they will view pop-ups,” along with tabbed browsing, built-in search, anti-phishing protection, and an extension system that let users add functionality. The archived release notes record that links opened by other applications could now open in a new tab, reuse a tab, or open a new window, and that Firefox shipped in many languages at launch.
Firefox arrived at a moment when Microsoft’s Internet Explorer held an overwhelming share of the browser market. By offering a fast, standards-focused alternative that users could download for free, Firefox gave web developers a reason to build for more than one browser again and helped restart competition on the web.
The renewed competition Firefox sparked, later joined by Apple’s Safari and Google’s Chrome, became known as the second browser war and pushed all browsers toward faster engines and better support for open web standards.