Firefox
free and open source web browser
Mozilla Firefox, or simply Firefox, is a free and open-source web browser developed by the Mozilla Foundation and its subsidiary, the Mozilla Corporation. It uses the Gecko rendering engine to display web pages, which implements current and anticipated web standards. The software is available for Windows, macOS, and Linux systems, as well as a mobile version for Android (see Firefox for Android) and iOS, with unofficial ports for other platforms such as Oracle Solaris and OpenIndiana.
Firefox is the spiritual successor of Netscape Navigator, as the Mozilla community was created by Netscape in 1998, before Netscape's acquisition by AOL. Firefox was created in 2002 under the codename "Phoenix" by members of the Mozilla community who desired a standalone browser rather than the Mozilla Application Suite bundle. During its beta phase, it proved to be popular with its testers and was praised for its speed, security, and add-ons compared to Microsoft's then-dominant Internet Explorer 6. It was released on November 9, 2004, and challenged Internet Explorer's dominance with 60 million downloads within nine months. In November 2017, Firefox began incorporating new technology under the code name "Quantum" to promote parallelism and a more intuitive user interface.
The current version of Firefox is available for Windows 10 or later versions of Windows, as well as macOS, and Linux. Its unofficial ports are available for various Unix systems such as Oracle Solaris and OpenIndiana, as well as for Unix-like operating systems, including FreeBSD, OpenBSD, NetBSD, and other operating systems, such as ReactOS. It is the default, pre-installed browser on Debian, Ubuntu, and some other Linux distros. Firefox is also available for Android and iOS. However, as with all other iOS web browsers, the iOS version uses the WebKit layout engine instead of Gecko due to platform requirements.
Begin with the source’s own compact description: “Firefox” is free and open source web browser. The dossier treats that line as a proposition to test through Firefox, free and source, not as a finished interpretation.
Why this record matters
The phrase “free and open source web browser” supplies a clear boundary for inquiry. It also exposes the unanswered questions: who defined that boundary, when it became stable and which sources sit outside it.
The citation trail is more important than the brevity of the summary: it shows where individual claims can be examined in context. The source revision retrieved here is dated Sep 23, 2026. The linked authority identifier is Q698. VIAF identifies the subject as 180493249. The Library of Congress control number is no2005045743. 7 of 27 selected statements include explicit references; 23 carry qualifiers and 0 use preferred rank. The first chronological checks are 1998, 2002, 2004 and 2017.
Overview language is designed for orientation and should not be treated as a substitute for the evidence cited beneath it. The source lead contains qualifying language; that uncertainty should survive quotation, summary and reuse. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
How to read it
Use the entry as an orientation point, then follow its citations and revision history. Names, dates and institutional relationships should be checked against the original record.
- Subject orientation
- Search vocabulary
- Locating named sources
The closest primary source, responsible institution and strongest cited specialist reference.
Three-step research path
- Establish the record: confirm the title “Firefox”, its source revision and the description used here.
- Expand the search: follow Firefox primary sources, Firefox archive and Firefox research across catalogues and specialist indexes.
- Test the account: compare the strongest cited source with the responsible institution’s current record and note any disagreement.
Questions for further research
- Which source most directly establishes the central claim about “Firefox”?
- Which institution is responsible for the underlying evidence?
- Which cited source is closest to the event, object or claim?
Search terms from this dossier
This entry incorporates text from “Firefox” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.