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Mozilla Firefox, or simply Firefox, is a
free and open-source Free and open-source software (FOSS) is a term used to refer to groups of software consisting of both free software and open-source software where anyone is freely licensed to use, copy, study, and change the software in any way, and the source ...
web browser A web browser is application software for accessing websites. When a user requests a web page from a particular website, the browser retrieves its files from a web server and then displays the page on the user's screen. Browsers are used on ...
developed by the
Mozilla Foundation The Mozilla Foundation (stylized as moz://a) is an American non-profit organization that exists to support and collectively lead the open source Mozilla project. Founded in July 2003, the organization sets the policies that govern development, ...
and its subsidiary, the
Mozilla Corporation The Mozilla Corporation (stylized as moz://a) is a wholly owned subsidiary of the Mozilla Foundation that coordinates and integrates the development of Internet-related applications such as the Firefox web browser, by a global community of open- ...
. It uses the
Gecko Geckos are small, mostly carnivorous lizards that have a wide distribution, found on every continent except Antarctica. Belonging to the infraorder Gekkota, geckos are found in warm climates throughout the world. They range from . Geckos ar ...
rendering engine Rendering or image synthesis is the process of generating a photorealistic or non-photorealistic image from a 2D or 3D model by means of a computer program. The resulting image is referred to as the render. Multiple models can be defined ...
to display web pages, which implements current and anticipated web standards. In November 2017, Firefox began incorporating new technology under the code name "
Quantum In physics, a quantum (plural quanta) is the minimum amount of any physical entity (physical property) involved in an interaction. The fundamental notion that a physical property can be "quantized" is referred to as "the hypothesis of quantizati ...
" to promote parallelism and a more intuitive
user interface In the industrial design field of human–computer interaction, a user interface (UI) is the space where interactions between humans and machines occur. The goal of this interaction is to allow effective operation and control of the machine f ...
. Firefox is available for
Windows 7 Windows 7 is a major release of the Windows NT operating system developed by Microsoft. It was released to manufacturing on July 22, 2009, and became generally available on October 22, 2009. It is the successor to Windows Vista, released nearly ...
and later versions,
macOS macOS (; previously OS X and originally Mac OS X) is a Unix operating system developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac computers. Within the market of desktop and lapt ...
, and
Linux Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, which ...
. Its unofficial ports are available for various
Unix Unix (; trademarked as UNIX) is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, and ot ...
and
Unix-like A Unix-like (sometimes referred to as UN*X or *nix) operating system is one that behaves in a manner similar to a Unix system, although not necessarily conforming to or being certified to any version of the Single UNIX Specification. A Unix-li ...
operating systems, including
FreeBSD FreeBSD is a free and open-source Unix-like operating system descended from the Berkeley Software Distribution (BSD), which was based on Research Unix. The first version of FreeBSD was released in 1993. In 2005, FreeBSD was the most popular ...
,
OpenBSD OpenBSD is a security-focused, free and open-source, Unix-like operating system based on the Berkeley Software Distribution (BSD). Theo de Raadt created OpenBSD in 1995 by forking NetBSD 1.0. According to the website, the OpenBSD project em ...
,
NetBSD NetBSD is a free and open-source Unix operating system based on the Berkeley Software Distribution (BSD). It was the first open-source BSD descendant officially released after 386BSD was forked. It continues to be actively developed and is a ...
,
illumos Illumos (stylized as illumos) is a partly free and open-source Unix operating system. It is based on OpenSolaris, which was based on System V Release 4 (SVR4) and the Berkeley Software Distribution (BSD). Illumos comprises a kernel, device ...
, and Solaris Unix. It is also available for Android and
iOS iOS (formerly iPhone OS) is a mobile operating system created and developed by Apple Inc. exclusively for its hardware. It is the operating system that powers many of the company's mobile devices, including the iPhone; the term also includes ...
. However, as with all other iOS web browsers, the iOS version uses the
WebKit WebKit is a browser engine developed by Apple and primarily used in its Safari web browser, as well as on the iOS and iPadOS version of any web browser. WebKit is also used by the BlackBerry Browser, PlayStation consoles beginning from the PS ...
layout engine instead of Gecko due to platform requirements. An optimized version is also available on the
Amazon Fire TV Amazon Fire TV (stylized as amazon fireTV) is a line of digital media players and microconsoles developed by Amazon. The devices are small network appliances that deliver digital audio and video content streamed via the Internet to a connecte ...
as one of the two main browsers available with Amazon's Silk Browser. Firefox was created in 2002 under the code name "Phoenix" by members of the
Mozilla Mozilla (stylized as moz://a) is a free software community founded in 1998 by members of Netscape. The Mozilla community uses, develops, spreads and supports Mozilla products, thereby promoting exclusively free software and open standards, wi ...
community who desired a standalone browser rather than the
Mozilla Application Suite The Mozilla Application Suite (originally known as Mozilla, marketed as the Mozilla Suite) is a discontinued cross-platform integrated Internet suite. Its development was initiated by Netscape Communications Corporation, before their acquisition ...
bundle. During its
beta Beta (, ; uppercase , lowercase , or cursive ; grc, βῆτα, bē̂ta or ell, βήτα, víta) is the second letter of the Greek alphabet. In the system of Greek numerals, it has a value of 2. In Modern Greek, it represents the voiced labiod ...
phase, it proved to be popular with its testers and was praised for its speed, security, and add-ons compared to
Microsoft Microsoft Corporation is an American multinational technology corporation producing computer software, consumer electronics, personal computers, and related services headquartered at the Microsoft Redmond campus located in Redmond, Washing ...
's then-dominant Internet Explorer 6. It was released on November 9, 2004, and challenged
Internet Explorer Internet Explorer (formerly Microsoft Internet Explorer and Windows Internet Explorer, commonly abbreviated IE or MSIE) is a series of graphical user interface, graphical web browsers developed by Microsoft which was used in the Microsoft Wind ...
's dominance with 60 million downloads within nine months. It is the
spiritual successor A spiritual successor (sometimes called a spiritual sequel) is a product or fictional work that is similar to, or directly inspired by, another previous work, but (unlike a traditional prequel or sequel) does not explicitly continue the product lin ...
of
Netscape Navigator Netscape Navigator was a web browser, and the original browser of the Netscape line, from versions 1 to 4.08, and 9.x. It was the flagship product of the Netscape Communications Corp and was the dominant web browser in terms of usage share in ...
, as the Mozilla community was created by
Netscape Netscape Communications Corporation (originally Mosaic Communications Corporation) was an American independent computer services company with headquarters in Mountain View, California and then Dulles, Virginia. Its Netscape web browser was onc ...
in 1998, before their acquisition by
AOL AOL (stylized as Aol., formerly a company known as AOL Inc. and originally known as America Online) is an American web portal and online service provider based in New York City. It is a brand marketed by the current incarnation of Yahoo (2017â ...
. Firefox usage share grew to a peak of 32.21% in November 2009, with Firefox 3.5 overtaking
Internet Explorer 7 Windows Internet Explorer 7 (IE7) (codenamed Rincon) is a web browser for Windows. It was released by Microsoft on October 18, 2006, as the seventh version of Internet Explorer and the successor to Internet Explorer 6. Internet Explorer 7 is par ...
, although not all versions of Internet Explorer as a whole; its usage then declined in competition with
Google Chrome Google Chrome is a cross-platform web browser developed by Google. It was first released in 2008 for Microsoft Windows, built with free software components from Apple WebKit and Mozilla Firefox. Versions were later released for Linux, macOS ...
. , according to
StatCounter StatCounter is a web traffic analysis website started in 1999. Access to basic services is free to use and advanced services can cost between and US$119 a month. StatCounter is based in Dublin, Ireland. The statistics from StatCounter are used ...
, it had a 7.1% usage share as a desktop web browser, making it the fourth-most popular desktop web browser after Google Chrome (66.1%),
Microsoft Edge Microsoft Edge is a proprietary, cross-platform web browser created by Microsoft. It was first released in 2015 as part of Windows 10 and Xbox One and later ported to other platforms as a fork of Google's Chromium open-source project: Android ...
(11.2%), and
Safari A safari (; ) is an overland journey to observe wild animals, especially in eastern or southern Africa. The so-called "Big Five" game animals of Africa – lion, leopard, rhinoceros, elephant, and Cape buffalo – particularly form an importa ...
(9.6%). Across all platforms, it again places fourth with a usage share of 3.04%.


History

The project began as an experimental branch of the
Mozilla project Mozilla (stylized as moz://a) is a free software community founded in 1998 by members of Netscape. The Mozilla community uses, develops, spreads and supports Mozilla products, thereby promoting exclusively free software and open standards, w ...
by
Dave Hyatt David Hyatt (born 28 June 1972) is an American software engineer and a ''Shadowrun'' game expansion author. Employed by Apple starting in 2002, he was part of the Safari web browser and WebKit framework development team. He also helped develop ...
, Joe Hewitt, and
Blake Ross Blake Aaron Ross (born June 12, 1985) is an American software engineer who is best known for his work as the co-creator of the Mozilla Firefox internet browser with Dave Hyatt. In 2005, he was nominated for ''Wired'' magazine's top Rave Award, R ...
. They believed the commercial requirements of
Netscape Netscape Communications Corporation (originally Mosaic Communications Corporation) was an American independent computer services company with headquarters in Mountain View, California and then Dulles, Virginia. Its Netscape web browser was onc ...
's sponsorship and developer-driven
feature creep Feature creep is the excessive ongoing expansion or addition of new features in a product, especially in computer software, video games and consumer and business electronics. These extra features go beyond the basic function of the product and ...
compromised the utility of the Mozilla browser. To combat what they saw as the
Mozilla Suite The Mozilla Application Suite (originally known as Mozilla, marketed as the Mozilla Suite) is a discontinued cross-platform integrated Internet suite. Its development was initiated by Netscape Communications Corporation, before their acquisition b ...
's
software bloat Software bloat is a process whereby successive versions of a computer program become perceptibly slower, use more memory, disk space or processing power, or have higher hardware requirements than the previous version, while making only dubious use ...
, they created a standalone browser, with which they intended to replace the Mozilla Suite. Version 0.1 was released on September 23, 2002. On April 3, 2003, the
Mozilla Organization The Mozilla Foundation (stylized as moz://a) is an American non-profit organization that exists to support and collectively lead the open source Mozilla project. Founded in July 2003, the organization sets the policies that govern development, ...
announced that it planned to change its focus from the Mozilla Suite to Firefox and
Thunderbird Thunderbird, thunder bird or thunderbirds may refer to: * Thunderbird (mythology), a legendary creature in certain North American indigenous peoples' history and culture * Ford Thunderbird, a car Birds * Dromornithidae, extinct flightless birds ...
. The Firefox project has undergone several name changes. The nascent browser was originally named Phoenix, after the mythical bird that rose triumphantly from the ashes of its dead predecessor (in this case, from the "ashes" of Netscape Navigator, after it was sidelined by Microsoft Internet Explorer in the "
First Browser War A browser war is competition for dominance in the usage share of web browsers. The "first browser war," (1995-2001) pitted Microsoft's Internet Explorer against Netscape's Navigator. Browser wars continued with the decline of Internet Explorer ...
"). Phoenix was renamed in 2003 due to a trademark claim from
Phoenix Technologies Phoenix Technologies Ltd is an American company that designs, develops and supports core system software for personal computers and other computing devices. The company's products commonly referred to as BIOS (Basic Input/Output System) or fir ...
. The replacement name, Firebird, provoked an intense response from the
Firebird Firebird and fire bird may refer to: Mythical birds * Phoenix (mythology), sacred firebird found in the mythologies of many cultures * Bennu, Egyptian firebird * Huma bird, Persian firebird * Firebird (Slavic folklore) Bird species ''Various sp ...
database software project. The Mozilla Foundation reassured them that the browser would always bear the name Mozilla Firebird to avoid confusion. After further pressure, Mozilla Firebird became Mozilla Firefox on February 9, 2004. The name Firefox was said to be derived from a nickname of the
red panda The red panda (''Ailurus fulgens''), also known as the lesser panda, is a small mammal native to the eastern Himalayas and southwestern China. It has dense reddish-brown fur with a black belly and legs, white-lined ears, a mostly white muzzle ...
, which became the mascot for the newly named project. For the abbreviation of Firefox, Mozilla prefers ''Fx'' or ''fx,'' although it is often abbreviated as ''FF''. The Firefox project went through many versions before version 1.0 and had already gained a great deal of acclaim from numerous media outlets, such as ''
Forbes ''Forbes'' () is an American business magazine owned by Integrated Whale Media Investments and the Forbes family. Published eight times a year, it features articles on finance, industry, investing, and marketing topics. ''Forbes'' also re ...
'' and ''
The Wall Street Journal ''The Wall Street Journal'' is an American business-focused, international daily newspaper based in New York City, with international editions also available in Chinese and Japanese. The ''Journal'', along with its Asian editions, is published ...
''. Among Firefox's popular features were the integrated pop-up blocker, tabbed browsing, and an extension mechanism for adding functionality. Although these features have already been available for some time in other browsers such as the
Mozilla Suite The Mozilla Application Suite (originally known as Mozilla, marketed as the Mozilla Suite) is a discontinued cross-platform integrated Internet suite. Its development was initiated by Netscape Communications Corporation, before their acquisition b ...
and
Opera Opera is a form of theatre in which music is a fundamental component and dramatic roles are taken by singers. Such a "work" (the literal translation of the Italian word "opera") is typically a collaboration between a composer and a librett ...
, Firefox was the first of these browsers to have achieved large-scale adoption. Firefox attracted attention as an alternative to
Internet Explorer Internet Explorer (formerly Microsoft Internet Explorer and Windows Internet Explorer, commonly abbreviated IE or MSIE) is a series of graphical user interface, graphical web browsers developed by Microsoft which was used in the Microsoft Wind ...
, which had come under fire for its alleged poor program design and insecurity—detractors cite IE's lack of support for certain Web standards, use of the potentially dangerous
ActiveX ActiveX is a deprecated software framework created by Microsoft that adapts its earlier Component Object Model (COM) and Object Linking and Embedding (OLE) technologies for content downloaded from a network, particularly from the World Wide Web. ...
component, and vulnerability to spyware and malware installation. Microsoft responded by releasing
Windows XP Windows XP is a major release of Microsoft's Windows NT operating system. It was released to manufacturing on August 24, 2001, and later to retail on October 25, 2001. It is a direct upgrade to its predecessors, Windows 2000 for high-end and ...
Service Pack 2, which added several important security features to Internet Explorer 6. Version 1.0 of Firefox was released on November 9, 2004. This was followed by version 1.5 in November 2005, version 2.0 in October 2006, version 3.0 in June 2008, version 3.5 in June 2009, version 3.6 in January 2010, and version 4.0 in March 2011. From version 5 onwards, the development and release model changed into a "rapid" one; by the end of 2011 the stable release was version 9, and by the end of 2012 it reached version 17. Major redesigns of its
graphical user interface The GUI ( "UI" by itself is still usually pronounced . or ), graphical user interface, is a form of user interface that allows users to interact with electronic devices through graphical icons and audio indicator such as primary notation, inste ...
occurred on versions 4.0 in March 2011, 29.0 "Australis" in April 2014, 57.0 "Quantum" in November 2017, and 89.0 "Proton" in June 2021. In 2016, Mozilla announced a project known as
Quantum In physics, a quantum (plural quanta) is the minimum amount of any physical entity (physical property) involved in an interaction. The fundamental notion that a physical property can be "quantized" is referred to as "the hypothesis of quantizati ...
, which sought to improve Firefox's Gecko engine and other components to improve the browser's performance, modernize its architecture, and transition the browser to a multi-process model. These improvements came in the wake of decreasing market share to
Google Chrome Google Chrome is a cross-platform web browser developed by Google. It was first released in 2008 for Microsoft Windows, built with free software components from Apple WebKit and Mozilla Firefox. Versions were later released for Linux, macOS ...
, as well as concerns that its performance was lapsing in comparison. Despite its improvements, these changes required existing add-ons for Firefox to be made incompatible with newer versions, in favor of a new
extension Extension, extend or extended may refer to: Mathematics Logic or set theory * Axiom of extensionality * Extensible cardinal * Extension (model theory) * Extension (predicate logic), the set of tuples of values that satisfy the predicate * E ...
system that is designed to be similar to Chrome and other recent browsers. Firefox 57, which was released in November 2017, was the first version to contain enhancements from Quantum, and has thus been named ''Firefox Quantum''. A Mozilla executive stated that Quantum was the "biggest update" to the browser since version 1.0. Unresponsive and crashing pages only affect other pages loaded within the same process. While Chrome uses separate processes for each loaded tab, Firefox distributes tabs over four processes by default since Quantum in order to balance memory consumption and performance. The process count can be adjusted, where more processes increase performance at the cost of memory, therefore suitable for computers with larger RAM capacity. On May 3, 2019, the expiration of an intermediate signing certificate on Mozilla servers caused Firefox to automatically disable and lock all browser extensions (add-ons). Mozilla began the roll-out of a fix shortly thereafter, using their Mozilla Studies component. On January 13, 2022, an issue with Firefox's HTTP/3 implementation resulted in a widespread outage for multiple hours.


Features

Features of the desktop edition include
tabbed browsing In interface design, a tab is a graphical user interface object that allows multiple documents or panels to be contained within a single window, using tabs as a navigational widget for switching between sets of documents. It is an interface ...
, full-screen mode,
spell checking In software, a spell checker (or spelling checker or spell check) is a software feature that checks for misspellings in a text file, text. Spell-checking features are often embedded in software or services, such as a word processor, email client, el ...
,
incremental search In computing, incremental search, hot search, incremental find or real-time suggestions is a user interface interaction method to progressively search for and filter through text. As the user types text, one or more possible matches for the text ...
,
smart bookmarks Smart bookmarks are an extended kind of Internet bookmark used in web browsers. By accepting an argument, they directly give access to functions of web sites, as opposed to filling web forms at the respective web site for accessing these functions. ...
, bookmarking and downloading through
drag and drop In computer graphical user interfaces, drag and drop is a pointing device gesture in which the user selects a virtual object by "grabbing" it and dragging it to a different location or onto another virtual object. In general, it can be used to ...
, a
download manager A download manager is a software tool that manages the downloading of files from the Internet, which may be built: into a Web browser, or as a, usually more sophisticated program Program, programme, programmer, or programming may refer to: Bu ...
,
user profile A user profile is a collection of settings and information associated with a user. It contains critical information that is used to identify an individual, such as their name, age, portrait photograph and individual characteristics such as ...
management,
private browsing Private browsing is a privacy feature in some web browsers. When operating in such a mode, the browser creates a temporary session that is isolated from the browser's main session and user data. Browsing history is not saved, and local data as ...
, bookmark tags, bookmark
exporting International trade is the exchange of capital, goods, and services across international borders or territories because there is a need or want of goods or services. (see: World economy) In most countries, such trade represents a significant ...
, offline mode, a
screenshot screenshot (also known as screen capture or screen grab) is a digital image that shows the contents of a computer display. A screenshot is created by the operating system or software running on the device powering the display. Additionally, s ...
tool,
web development tools Web development tools (often called devtools or inspect element) allow web developers to test and debug their code. They are different from website builders and integrated development environments (IDEs) in that they do not assist in the direct c ...
, a "page info" feature which shows a list of page metadata and multimedia items, a sophisticated configuration menu at about:config for
power user A power user is a user of computers, software and other electronic devices, who uses advanced features of computer hardware, operating systems, programs, or websites which are not used by the average user. A power user might not have extensive tec ...
s, and more location-aware browsing (also known as "
geolocation Geopositioning, also known as geotracking, geolocalization, geolocating, geolocation, or geoposition fixing, is the process of determining or estimating the geographic position of an object. Geopositioning yields a set of Geographic coordinate s ...
") based on a Google service. (section "''What information is being sent, and to whom? (...)''") Firefox has an integrated search system which uses Google by default in most markets but an update for American users in 2021 made it start including paid promotions by default in its suggestions.
DNS over HTTPS DNS over HTTPS (DoH) is a protocol for performing remote Domain Name System (DNS) resolution via the HTTPS protocol. A goal of the method is to increase user privacy and security by preventing eavesdropping and manipulation of DNS data by man-i ...
is another feature whose default behaviour is determined geographically. Firefox provides an environment for web developers in which they can use built-in tools, such as the Error Console or the
DOM Inspector DOM Inspector (DOMi) is a web developer tool created by Joe Hewitt and was originally included in Mozilla Application Suite as well as versions of Mozilla Firefox prior to Firefox 3 Mozilla Firefox 3.0 is a version of the Firefox web browser ...
, and
extensions Extension, extend or extended may refer to: Mathematics Logic or set theory * Axiom of extensionality * Extensible cardinal * Extension (model theory) * Extension (predicate logic), the set of tuples of values that satisfy the predicate * Ex ...
, such as Firebug and more recently there has been an integration feature with
Pocket A pocket is a bag- or envelope-like receptacle either fastened to or inserted in an article of clothing to hold small items. Pockets are also attached to luggage, backpacks, and similar items. In older usage, a pocket was a separate small bag o ...
. Firefox Hello was an implementation of
WebRTC WebRTC (Web Real-Time Communication) is a free and open-source project providing web browsers and mobile applications with real-time communication (RTC) via application programming interfaces (APIs). It allows audio and video communication to wor ...
, added in October 2014, which allows users of Firefox and other compatible systems to have a video call, with the extra feature of screen and file sharing by sending a link to each other. Firefox Hello was scheduled to be removed in September 2016. Former features include a
File Transfer Protocol The File Transfer Protocol (FTP) is a standard communication protocol used for the transfer of computer files from a server to a client on a computer network. FTP is built on a client–server model architecture using separate control and data ...
(FTP) client for browsing file servers, the ability to block images from individual domains (until version 72), a 3D page inspector (versions 11 to 46), tab grouping (until version 44), and the ability to add customized extra toolbars (until version 28).


Browser extensions

Functions can be added through add-ons created by
third-party developer A video game developer is a broad term for a software developer specializing in video game development – the process and related disciplines of creating video games. A game developer can range from one person who undertakes all tasks to a large ...
s. Add-ons are primarily coded using an
HTML The HyperText Markup Language or HTML is the standard markup language for documents designed to be displayed in a web browser. It can be assisted by technologies such as Cascading Style Sheets (CSS) and scripting languages such as JavaScri ...
,
CSS Cascading Style Sheets (CSS) is a style sheet language used for describing the presentation of a document written in a markup language such as HTML or XML (including XML dialects such as SVG, MathML or XHTML). CSS is a cornerstone techno ...
,
JavaScript JavaScript (), often abbreviated as JS, is a programming language that is one of the core technologies of the World Wide Web, alongside HTML and CSS. As of 2022, 98% of Website, websites use JavaScript on the Client (computing), client side ...
, with
API An application programming interface (API) is a way for two or more computer programs to communicate with each other. It is a type of software Interface (computing), interface, offering a service to other pieces of software. A document or standa ...
known as WebExtensions, which is designed to be compatible with
Google Chrome Google Chrome is a cross-platform web browser developed by Google. It was first released in 2008 for Microsoft Windows, built with free software components from Apple WebKit and Mozilla Firefox. Versions were later released for Linux, macOS ...
and
Microsoft Edge Microsoft Edge is a proprietary, cross-platform web browser created by Microsoft. It was first released in 2015 as part of Windows 10 and Xbox One and later ported to other platforms as a fork of Google's Chromium open-source project: Android ...
extension systems. Firefox previously supported add-ons using the
XUL XUL ( ), which stands for XML User Interface Language, is a user interface markup language developed by Mozilla. XUL is an XML dialect for writing graphical user interfaces, enabling developers to write user interface elements in a manner sim ...
and
XPCOM Cross Platform Component Object Model (XPCOM) is a cross-platform component model from Mozilla. It is similar to Microsoft Component Object Model (COM) and Common Object Request Broker Architecture (CORBA). It features multiple language bindings an ...
APIs, which allowed them to directly access and manipulate much of the browser's internal functionality. As compatibility was not included in the multi-process architecture, XUL add-ons have been deemed ''Legacy add-ons'' and are no longer supported on Firefox 57 "Quantum" and newer. Mozilla has occasionally installed extensions for users without their permission. This happened in 2017 when an extension designed to promote the show
Mr Robot ''Mr. Robot'' is an American drama thriller television series created by Sam Esmail for USA Network. It stars Rami Malek as Elliot Alderson, a cybersecurity engineer and hacker with social anxiety disorder, clinical depression and dissociati ...
was silently added in an update to Firefox.


Themes

Firefox can have themes added to it, which users can create or download from third parties to change the appearance of the browser.


Guest session

In 2013, Firefox for Android added a ''guest session'' mode, which wiped browsing data such as tabs, cookies, and history at the end of each guest session. Guest session data was kept even when restarting the browser or device, and deleted only upon a manual exit. The feature was removed in 2019, purportedly to "''streamline the experience''".


Standards

Firefox implements many
web standards Web standards are the formal, non-proprietary standards and other technical specifications that define and describe aspects of the World Wide Web. In recent years, the term has been more frequently associated with the trend of endorsing a set of s ...
, including
HTML4 The HyperText Markup Language or HTML is the standard markup language for documents designed to be displayed in a web browser. It can be assisted by technologies such as Cascading Style Sheets (CSS) and scripting languages such as JavaScri ...
(almost full
HTML5 HTML5 is a markup language used for structuring and presenting content on the World Wide Web. It is the fifth and final major HTML version that is a World Wide Web Consortium (W3C) recommendation. The current specification is known as the HTML ...
),
XML Extensible Markup Language (XML) is a markup language and file format for storing, transmitting, and reconstructing arbitrary data. It defines a set of rules for encoding documents in a format that is both human-readable and machine-readable. T ...
,
XHTML Extensible HyperText Markup Language (XHTML) is part of the family of XML markup languages. It mirrors or extends versions of the widely used HyperText Markup Language (HTML), the language in which Web pages are formulated. While HTML, prior ...
,
MathML Mathematical Markup Language (MathML) is a mathematical markup language, an application of XML for describing mathematical notations and capturing both its structure and content. It aims at integrating mathematical formulae into World Wide Web ...
, SVG 1.1 (full), SVG 2 (partial),
CSS Cascading Style Sheets (CSS) is a style sheet language used for describing the presentation of a document written in a markup language such as HTML or XML (including XML dialects such as SVG, MathML or XHTML). CSS is a cornerstone techno ...
(with extensions), ECMAScript (
JavaScript JavaScript (), often abbreviated as JS, is a programming language that is one of the core technologies of the World Wide Web, alongside HTML and CSS. As of 2022, 98% of Website, websites use JavaScript on the Client (computing), client side ...
),
DOM Dom or DOM may refer to: People and fictional characters * Dom (given name), including fictional characters * Dom (surname) * Dom La Nena (born 1989), stage name of Brazilian-born cellist, singer and songwriter Dominique Pinto * Dom people, an et ...
,
XSLT XSLT (Extensible Stylesheet Language Transformations) is a language originally designed for transforming XML documents into other XML documents, or other formats such as HTML for web pages, plain text or XSL Formatting Objects, which may subseque ...
,
XPath XPath (XML Path Language) is an expression language designed to support the query or transformation of XML documents. It was defined by the World Wide Web Consortium (W3C) and can be used to compute values (e.g., strings, numbers, or Boolean v ...
, and
APNG Animated Portable Network Graphics (APNG) is a file format which extends the Portable Network Graphics (PNG) specification to permit animated images that work similarly to animated GIF files, while supporting 24-bit images and 8-bit transparenc ...
(Animated PNG) images with
alpha transparency In computer graphics, alpha compositing or alpha blending is the process of combining one image with a background to create the appearance of partial or full transparency. It is often useful to render picture elements (pixels) in separate pas ...
. Firefox also implements standards proposals created by the
WHATWG The Web Hypertext Application Technology Working Group (WHATWG) is a community of people interested in evolving HTML and related technologies. The WHATWG was founded by individuals from Apple Inc., the Mozilla Foundation and Opera Software, lea ...
such as client-side storage, and the
canvas element The canvas element is part of HTML5 and allows for dynamic, scriptable rendering of 2D shapes and bitmap images. It is a low level, procedural model that updates a bitmap. HTML5 Canvas also helps in making 2D games. While the HTML5 canvas off ...
. These standards are implemented through the Gecko layout engine, and
SpiderMonkey SpiderMonkey is the first JavaScript engine, written by Brendan Eich at Netscape Communications, later released as open source and currently maintained by the Mozilla Foundation. It is used in the Firefox web browser. History Eich "wrote Jav ...
JavaScript engine. Firefox 4 was the first release to introduce significant HTML5 and CSS3 support. Firefox has passed the
Acid2 Acid2 is a webpage that test web browsers' functionality in displaying aspects of HTML markup, CSS 2.1 styling, PNG images, and data URIs. The test page was released on 13 April 2005 by the Web Standards Project. The Acid2 test page will be ...
standards-compliance test since version 3.0. Mozilla had originally stated that they did not intend for Firefox to pass the
Acid3 The Acid3 test is a web test page from the Web Standards Project that checks a web browser's compliance with elements of various web standards, particularly the Document Object Model (DOM) and JavaScript. If the test is successful, the results ...
test fully because they believed that the SVG fonts part of the test had become outdated and irrelevant, due to
WOFF The Web Open Font Format (WOFF) is a font format for use in web pages. WOFF files are OpenType or TrueType fonts, with format-specific compression applied and additional XML metadata added. The two primary goals are first to distinguish font file ...
being agreed upon as a standard by all major browser makers. Because the SVG font tests were removed from the Acid3 test in September 2011, Firefox 4 and greater scored 100/100. Firefox also implements "Safe Browsing," a
proprietary protocol In telecommunications, a proprietary protocol is a communications protocol owned by a single organization or individual. Intellectual property rights and enforcement Ownership by a single organization gives the owner the ability to place restricti ...
from Google used to exchange data related with phishing and malware protection. Since version 38 on
Windows Vista Windows Vista is a major release of the Windows NT operating system developed by Microsoft. It was the direct successor to Windows XP, which was released five years before, at the time being the longest time span between successive releases of ...
and newer, Firefox supports the playback of video content protected by HTML5
Encrypted Media Extensions Encrypted Media Extensions (EME) is a W3C specification for providing a communication channel between web browsers and the Content Decryption Module (CDM) software which implements digital rights management (DRM). This allows the use of HTML5 vi ...
(EME). For security and privacy reasons, EME is implemented within a wrapper of open-source code that allows execution of a
proprietary {{Short pages monitor As a workaround for the issue, a preloader application was created that loaded components of Firefox on startup, similar to Internet Explorer. A Windows Vista feature called
SuperFetch Windows Vista introduced a number of new I/O functions to the Microsoft Windows line of operating systems. They are intended to shorten the time taken to boot the system, improve the responsiveness of the system, and improve the reliability of dat ...
performs a similar task of preloading Firefox if it is used often enough. Tests performed by ''
PC World ''PC World'' (stylized as PCWorld) is a global computer magazine published monthly by IDG. Since 2013, it has been an online only publication. It offers advice on various aspects of PCs and related items, the Internet, and other personal tech ...
'' and Zimbra in 2006 indicated that Firefox 2 used less memory than Internet Explorer 7. Firefox 3 used less memory than Internet Explorer 7, Opera 9.50 Beta,
Safari A safari (; ) is an overland journey to observe wild animals, especially in eastern or southern Africa. The so-called "Big Five" game animals of Africa – lion, leopard, rhinoceros, elephant, and Cape buffalo – particularly form an importa ...
3.1 Beta, and Firefox 2 in tests performed by Mozilla, CyberNet, and The Browser World. In mid-2009, BetaNews benchmarked Firefox 3.5 and declared that it performed "nearly ten times better on XP than Microsoft Internet Explorer 7".


2010s

In January 2010, Lifehacker compared the performance of Firefox 3.5, Firefox 3.6, Google Chrome 4 (stable and Dev versions), Safari 4, and Opera (10.1 stable and 10.5 pre-alpha versions). Lifehacker timed how long browsers took to start and reach a page (both right after boot-up and after running at least once already), timed how long browsers took to load nine tabs at once, tested JavaScript speeds using Mozilla's Dromaeo online suite (which implements Apple's
SunSpider A browser speed test is a computer benchmark that scores the performance of a web browser, by measuring the browser's efficiency in completing a predefined list of tasks. In general the testing software is available online, located on a website, w ...
and Google's V8 tests) and measured memory usage using Windows 7's process manager. They concluded that Firefox 3.5 and 3.6 were the fifth- and sixth-fastest browsers, respectively, on startup, 3.5 was third- and 3.6 was sixth-fastest to load nine tabs at once, 3.5 was sixth- and 3.6 was fifth-fastest on the JavaScript tests. They also concluded that Firefox 3.6 was the most efficient with memory usage followed by Firefox 3.5. In February 2012, ''
Tom's Hardware ''Tom's Hardware'' is an online publication owned by Future plc and focused on technology. It was founded in 1996 by Thomas Pabst. It provides articles, news, price comparisons, videos and reviews on computer hardware and high technology. The si ...
'' performance tested Chrome 17, Firefox 10,
Internet Explorer 9 Internet Explorer 9 or IE9 (officially Windows Internet Explorer 9) is a web browser for Windows. It was released by Microsoft on March 14, 2011, as the ninth version of Internet Explorer and the successor to Internet Explorer 8, and can replace p ...
, Opera 11.61, and Safari 5.1.2 on Windows 7. ''Tom's Hardware'' summarized their tests into four categories: Performance, Efficiency, Reliability, and Conformance. In the performance category they tested
HTML5 HTML5 is a markup language used for structuring and presenting content on the World Wide Web. It is the fifth and final major HTML version that is a World Wide Web Consortium (W3C) recommendation. The current specification is known as the HTML ...
,
Java Java (; id, Jawa, ; jv, ꦗꦮ; su, ) is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea to the north. With a population of 151.6 million people, Java is the world's List ...
,
JavaScript JavaScript (), often abbreviated as JS, is a programming language that is one of the core technologies of the World Wide Web, alongside HTML and CSS. As of 2022, 98% of Website, websites use JavaScript on the Client (computing), client side ...
,
DOM Dom or DOM may refer to: People and fictional characters * Dom (given name), including fictional characters * Dom (surname) * Dom La Nena (born 1989), stage name of Brazilian-born cellist, singer and songwriter Dominique Pinto * Dom people, an et ...
,
CSS 3 Cascading Style Sheets (CSS) is a style sheet language used for describing the presentation of a document written in a markup language such as HTML or XML (including XML dialects such as SVG, MathML or XHTML). CSS is a cornerstone technol ...
,
Flash Flash, flashes, or FLASH may refer to: Arts, entertainment, and media Fictional aliases * Flash (DC Comics character), several DC Comics superheroes with super speed: ** Flash (Barry Allen) ** Flash (Jay Garrick) ** Wally West, the first Kid ...
,
Silverlight Microsoft Silverlight is a discontinued application framework designed for writing and running rich web applications, similar to Adobe Inc., Adobe's Run time environment, runtime, Adobe Flash. A plugin for Silverlight is still available for a v ...
, and
WebGL WebGL (Short for Web Graphics Library) is a JavaScript API for rendering interactive 2D and 3D graphics within any compatible web browser without the use of plug-ins. WebGL is fully integrated with other web standards, allowing GPU-accelerated ...
(
WebGL 2 WebGL (Short for Web Graphics Library) is a JavaScript API for rendering interactive 2D and 3D graphics within any compatible web browser without the use of plug-ins. WebGL is fully integrated with other web standards, allowing GPU-accelerated ...
is current as of version 51; and Java and Silverlight stop working as of version 52)—they also tested startup time and page load time. The performance tests showed that Firefox was either "acceptable" or "strong" in most categories, winning three categories (HTML5, HTML5
hardware acceleration Hardware acceleration is the use of computer hardware designed to perform specific functions more efficiently when compared to software running on a general-purpose central processing unit (CPU). Any transformation of data that can be calcula ...
, and Java) only finishing "weak" in CSS performance. In the efficiency tests, ''Tom's Hardware'' tested memory usage and management. In this category, it determined that Firefox was only "acceptable" at performing light memory usage, while it was "strong" at performing heavy memory usage. In the reliability category, Firefox performed a "strong" amount of proper page loads. In the final category, conformance, it was determined that Firefox had "strong" conformance for JavaScript and HTML5. In conclusion, ''Tom's Hardware'' determined that Firefox was the best browser for Windows 7 OS, but that it only narrowly beat Google Chrome. In June 2013, ''Tom's Hardware'' again performance tested Firefox 22, Chrome 27, Opera 12, and
Internet Explorer 10 Internet Explorer 10 (IE10) is the tenth, and by now, discontinued, version of the Internet Explorer web browser and the successor to Internet Explorer 9, released by Microsoft on September 4, 2012, shortly after the completion of Windows Serv ...
. They found that Firefox slightly edged out the other browsers in their "performance" index, which examined wait times, JavaScript execution speed, HTML5/CSS3 rendering, and hardware acceleration performance. Firefox also scored the highest on the "non-performance" index, which measured memory efficiency, reliability, security, and standards conformance, finishing ahead of Chrome, the runner-up. ''Tom's Hardware'' concluded by declaring Firefox the "sound" winner of the performance benchmarks. In January 2014, a benchmark testing the memory usage of Firefox 29, Google Chrome 34, and
Internet Explorer 11 Internet Explorer 11 (IE11) is the eleventh, final, and now deprecated version of the Internet Explorer web browser. It was initially included in the release of Windows 8.1, Windows RT 8.1 and Windows Server 2012 R2 on October 17, 2013, and was ...
indicated that Firefox used the least memory when a substantial number of tabs were open. In benchmark testing in early 2015 on a "high-end" Windows machine, comparing
Microsoft Edge Microsoft Edge is a proprietary, cross-platform web browser created by Microsoft. It was first released in 2015 as part of Windows 10 and Xbox One and later ported to other platforms as a fork of Google's Chromium open-source project: Android ...
, Internet Explorer, Firefox, Chrome, and Opera, Firefox achieved the highest score on three of the seven tests. Four different JavaScript performance tests gave conflicting results. Firefox surpassed all other browsers on the Peacekeeper benchmark but was behind the Microsoft products when tested with SunSpider. Measured with Mozilla's Kraken, it came second place to Chrome, while on Google's
Octane Octane is a hydrocarbon and an alkane with the chemical formula , and the condensed structural formula . Octane has many structural isomers that differ by the amount and location of branching in the carbon chain. One of these isomers, 2,2,4-Tri ...
challenge it took third behind Chrome and Opera. Firefox took the lead with WebXPRT, which runs several typical HTML5 and JavaScript tasks. Firefox, Chrome, and Opera all achieved the highest possible score on the Oort Online test, measuring WebGL rendering speed (WebGL 2 is now current). In terms of HTML5 compatibility testing, Firefox was ranked in the middle of the group. A similar set of benchmark tests in 2016 showed Firefox's JavaScript performance on Kraken and the newer
Jetstream Jet streams are fast flowing, narrow, meandering air currents in the atmospheres of some planets, including Earth. On Earth, the main jet streams are located near the altitude of the tropopause and are westerly winds (flowing west to east) ...
tests trailing slightly behind all other tested browsers except Internet Explorer (IE), which performed relatively poorly. On Octane, Firefox came ahead of IE and Safari, but again slightly behind the rest, including
Vivaldi Antonio Lucio Vivaldi (4 March 1678 â€“ 28 July 1741) was an Italian composer, virtuoso violinist and impresario of Baroque music. Regarded as one of the greatest Baroque composers, Vivaldi's influence during his lifetime was widespread a ...
and Microsoft Edge. Edge took overall first place on the Jetstream and Octane benchmarks.


Firefox Quantum

As of the adoption of Firefox 57 and Mozilla's Quantum project entering production browsers in November 2017, Firefox was tested to be faster than Chrome in independent JavaScript tests, and demonstrated to use less memory with many browser tabs opened.
TechRadar ''TechRadar'' is an online publication owned by Future and focused on technology. It has editorial teams in the US, UK and Australia and provides news and reviews of tech products and gadgets. It was launched in 2007 and expanded to the US in ...
rated it as the fastest web browser in a May 2019 report.


Usage share

Downloads have continued at an increasing rate since Firefox 1.0 was released on November 9, 2004, and Firefox had already been downloaded over one billion times. This number does not include downloads using software updates or those from third-party websites. They do not represent a user count, as one download may be installed on many machines, one person may download the software multiple times, or the software may be obtained from a third-party. In July 2010, IBM asked all employees (about 400,000) to use Firefox as their default browser. Firefox was the second-most used web browser until November 2011, when Google Chrome surpassed it. According to Mozilla, Firefox has more than 450 million users . Up to early 2020, Firefox was the second-most widely used desktop browser, and that position made it the third-most popular with 3.82% of worldwide
usage share of web browsers The usage share of web browsers is the portion, often expressed as a percentage, of visitors to a group of web sites that use a particular web browser. Accuracy Measuring browser usage in the number of requests (page hits) made by each use ...
across all platforms. According to the Firefox Public Data report by Mozilla, the active monthly count of Desktop clients has decreased from around 310 million in 2017 to 260 million in 2019. From Oct 2020, the desktop market share of Firefox started to decline in countries where it used to be the most popular. In Eritrea, it dropped from 50% in Oct 2020 to 9.32% in Sept 2021. In Cuba, it dropped from 54.36% in Sept 2020 to 38.42% in Sept 2021.


Third-party forks

Web browsers based on Firefox Web most often refers to: * Spider web, a silken structure created by the animal * World Wide Web or the Web, an Internet-based hypertext system Web, WEB, or the Web may also refer to: Computing * WEB, a literate programming system created by ...
include: *
Abrowser Trisquel (full name Trisquel GNU/Linux) is a computer operating system, a Linux distribution, derived from another distribution, Ubuntu. The project aims for a fully free software system without proprietary software or firmware and uses a version ...
*
Basilisk In European bestiaries and legends, a basilisk ( or ) is a legendary reptile reputed to be a serpent king, who causes death to those who look into its eyes. According to the ''Naturalis Historia'' of Pliny the Elder, the basilisk of Cyrene is ...
*
Classilla Classilla is a Gecko-based Internet suite for PowerPC-based classic Macintosh operating systems, essentially an updated descendant of the defunct Mozilla Application Suite by way of the Mac OS port maintained in the aborteWaMComproject. The name ...
*
Cliqz Cliqz was a privacy-oriented web browser and search engine developed by Cliqz GmbH and majority-owned by Hubert Burda Media. It was available as a desktop and mobile web browser as well as an extension for Firefox itself. Composition It is ...
*
Comodo IceDragon Comodo IceDragon was a Firefox-based open source web browser from the Comodo Group for Microsoft Windows. Features * Firefox-based: IceDragon 61 is based on the Firefox 61 codebase. It provides detection for Firefox hard-coded plugin installa ...
* ''
Ghostery Ghostery is a free and open-source privacy and security-related browser extension and mobile browser application. Since February 2017, it has been owned by the German company Cliqz International GmbH (formerly owned by Evidon, Inc., which wa ...
Dawn'' *
GNU IceCat GNU IceCat, formerly known as GNU IceWeasel, is a completely free version of the Mozilla Firefox web browser distributed by the GNU Project. It is compatible with Linux, Windows, Android and macOS. IceCat is released as a part of GNUzilla, G ...
*
K-Meleon K-Meleon is a free and open-source, lightweight web browser for Microsoft Windows. Unlike cross-platform browsers, it uses the native Windows API to create its user interface. K-Meleon can use the secure Goanna layout engine based on Mozilla's ...
* LibreWolf, a fork focused on privacy and security *
Light Browser Light or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 ter ...
* Mull Browser *
Pale Moon Pale Moon is an open-source web browser with an emphasis on customization; its motto is "Your browser, Your way". There are official releases for Microsoft Windows and Linux, as well as contributed builds for various platforms. Pale Moon origi ...
* ''Parrotgeek Firefox Legacy'' (for
Mac OS X macOS (; previously OS X and originally Mac OS X) is a Unix operating system developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac (computer), Mac computers. Within the market of ...
) * Swiftweasel * TenFourFox *
Tor browser Tor, short for The Onion Router, is free and open-source software for enabling anonymous communication. It directs Internet traffic through a free, worldwide, volunteer overlay network, consisting of more than seven thousand relays, to conc ...
*
Waterfox Waterfox is an open-source web browser that is forked from Firefox and developed by System1. There are official Waterfox releases for Windows, macOS, and Linux. Divisions Waterfox Waterfox shares core features and technologies like the Gecko b ...
* Wild Fox


See also

* Firefox User Extension Library *
History of the web browser A web browser is a software application for retrieving, presenting and traversing information resources on the World Wide Web. It further provides for the capture or input of information which may be returned to the presenting system, then store ...
*
List of free and open-source software packages This is a list of free and open-source software packages, computer software licensed under free software licenses and open-source licenses. Software that fits the Free Software Definition may be more appropriately called free software; the GNU p ...
*
Mozilla Prism Mozilla Prism (formerly WebRunner) is a discontinued project which integrated web applications with the desktop, allowing web applications to be launched from the desktop and configured independently of the default web browser. As of November 201 ...
*
XULRunner XULRunner is a discontinued, packaged version of the Mozilla platform to enable standalone desktop application development using XUL, developed by Mozilla. It replaced the ''Gecko Runtime Environment'', a stalled project with a similar purpose. T ...


References


Further reading

* * * * * * *


External links

* *
Firefox
at
Microsoft Store Microsoft Store (formerly known as Windows Store) is a digital distribution platform operated by Microsoft. It started as an app store for Windows 8 and Windows Server 2012 as the primary means of distributing Universal Windows Platform apps ...
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