What is Firefox?
Firefox is a web browser for Windows, macOS, Linux, Android and iOS. Except on iOS, where it uses Apple’s WebKit engine because of Apple’s platform rules, it displays pages with Gecko, Mozilla’s own rendering engine, which makes Firefox one of the few major browsers not built on Google’s Chromium project. Since the Quantum overhaul of 2017, parts of Gecko have been rewritten in Rust, a systems programming language that Mozilla sponsored in its early years.
Privacy is central to how Mozilla presents the browser. Enhanced Tracking Protection blocks many known trackers, cross-site tracking cookies and cryptominers by default, and Total Cookie Protection keeps each site’s cookies in a separate jar. Users can install add-ons from Mozilla’s catalog on desktop and Android, sync bookmarks, passwords and open tabs through a Mozilla account, translate pages with models that run on the device, and organize windows with vertical tabs and tab groups, both added in 2025.
Mozilla ships a new version of Firefox about every four weeks, plus an Extended Support Release for organizations that prefer fewer changes. The browser has gained AI features, including an optional sidebar for chatbots such as ChatGPT and Claude. After CEO Anthony Enzor-DeMeo said in December 2025 that Firefox would evolve into a modern AI browser, Firefox 148 introduced an AI controls section in February 2026 with a single setting that blocks the browser’s AI enhancements. StatCounter estimated Firefox’s worldwide usage share at 2.98 percent across all devices and 5.31 percent on desktop in August 2026.
Key features of Firefox
- 01
Gecko rendering engine
Firefox renders web pages with Mozilla’s Gecko engine and runs scripts with its SpiderMonkey JavaScript engine, giving the web an implementation of its standards that is independent of Chromium and WebKit.
- 02
Enhanced Tracking Protection
Turned on by default, it blocks many social media trackers, cross-site tracking cookies, cryptominers and fingerprinting scripts, with a strict mode and custom settings for people who want more blocking.
- 03
Total Cookie Protection
Each website gets its own cookie jar, so cookies set while visiting one site cannot be read by trackers embedded on other sites to follow a person around the web.
- 04
Extensions
The addons.mozilla.org catalog offers ad blockers, password managers and Mozilla’s Multi-Account Containers, and Firefox continues to support the blocking web request API that many content blockers rely on.
- 05
Sync across devices
Signing in with a Mozilla account syncs bookmarks, history, passwords, open tabs and add-ons between desktop and mobile versions of Firefox, with the synced data encrypted end to end.
- 06
On-device translation
Firefox can translate web pages between many languages using machine translation models that run locally, so the page’s text does not have to be sent to a cloud translation service.
- 07
Tab management
Vertical tabs, tab groups, pinned tabs and Picture-in-Picture video help people keep many open pages organized and watch a video in a floating window while they browse.
- 08
AI controls
Since Firefox 148 in 2026, a settings section lets users turn individual AI features such as the chatbot sidebar on or off, or block the browser’s AI enhancements entirely.
Who uses Firefox?
- Privacy-conscious people choose Firefox for its default tracking protection and for its independence from Google’s Chromium engine.
- Web developers test sites in Firefox and use its built-in developer tools to inspect layouts, debug JavaScript and check compatibility with Gecko.
- Organizations deploy the Extended Support Release and manage browser settings through enterprise policies on Windows, macOS and Linux computers.
- Many Linux users get Firefox as the default browser in distributions such as Ubuntu and Fedora.
- Android users who want content blocking on their phones install extensions such as uBlock Origin in Firefox for Android.
History of Firefox
Firefox began in 2002 as Phoenix, an experimental browser that Dave Hyatt, Joe Hewitt and Blake Ross built inside the Mozilla project as a lighter alternative to the full Mozilla Application Suite. Naming conflicts with other software led to a rename to Firebird in 2003 and then to Firefox in February 2004. Version 1.0 arrived on November 9, 2004, and volunteers funded a two-page advertisement in The New York Times to promote it as Internet Explorer’s dominance began to slip.
Chrome’s arrival in 2008 turned Google, Firefox’s main search partner, into its strongest rival. Mozilla answered with a faster release schedule in 2011 and, in November 2017, Firefox Quantum, which rebuilt major parts of the engine for speed and parallel processing. A rebuilt Firefox for Android followed in 2020. In February 2025 Mozilla introduced Terms of Use for Firefox and revised their wording within days after users objected to broad language about their data, and in 2026 it added controls that let users switch off AI features.
- 2002
Phoenix 0.1, the browser that later becomes Firefox, is released in September.
- 2004
The browser takes the Firefox name in February and reaches version 1.0 on November 9.
- 2011
Mozilla adopts a rapid release cycle with a new Firefox version every six weeks.
- 2017
Firefox Quantum rebuilds major parts of the browser engine for speed.
- 2019
Enhanced Tracking Protection is switched on by default for Firefox users.
- 2020
Mozilla releases a rebuilt Firefox for Android based on its GeckoView engine.
- 2025
Vertical tabs and tab groups arrive, and Mozilla introduces Terms of Use for Firefox.
- 2026
Firefox 148 adds AI controls, including an option to block AI features entirely.
Firefox pricing
Pricing modelFree and open source
Free to download and use; Mozilla earns money mainly from search partnerships and advertising rather than charging users.
Prices change often. Check the official Firefox website for current plans.
Firefox alternatives
Well-known alternativesGoogle Chrome, Safari, Microsoft Edge, Brave, Opera and Vivaldi
Firefox: frequently asked questions
Who makes Firefox?
Firefox is made by Mozilla Corporation, a subsidiary of the non-profit Mozilla Foundation, together with volunteer contributors around the world. Mozilla Corporation is based in San Francisco and has been led by CEO Anthony Enzor-DeMeo since December 2025.
What is Firefox used for?
Firefox is used to browse the web on computers and phones. People use it for everyday browsing, private browsing with tracking protection, running extensions such as ad blockers and syncing bookmarks and passwords across devices, and web developers use its tools to test and debug websites.
Is Firefox free?
Yes. Firefox is free to download and use, and its source code is available under the Mozilla Public License 2.0. Mozilla earns money mainly from search partners such as Google, which pay to be built into the browser, and from advertising and optional paid services.
When was Firefox released?
Firefox 1.0 was released on November 9, 2004. The browser first appeared as a preview called Phoenix in September 2002 and was renamed Firebird in 2003 before adopting the Firefox name in February 2004.
Is Firefox based on Chromium?
No. Firefox on Windows, macOS, Linux and Android uses Mozilla’s own Gecko engine rather than Google’s Chromium, which underlies Chrome, Edge, Opera and Brave. The iOS version of Firefox uses Apple’s WebKit engine because of Apple’s platform rules.
Can AI features be turned off in Firefox?
Yes. Firefox 148, released in February 2026, added an AI controls section to the browser’s settings. Users can switch off individual features, such as the AI chatbot sidebar, or use a single setting to block Firefox’s AI enhancements entirely.
Sources
- Firefox firefox.com
- Browser Market Share Worldwide, Statcounter Global Stats gs.statcounter.com
- Firefox 148 Now Available With The New AI Controls, Phoronix phoronix.com
- Firefox, Wikipedia en.wikipedia.org
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