Category: Computers/Technology

Mozilla Firefox

Logo used since October 2019
Developer(s)	Mozilla Foundation and its contributors Mozilla Corporation
Initial release	November 9, 2004; 19 years ago (2004-11-09)
Stable release(s) [±]
Standard 127.0.2[1]  / June 25, 2024; 5 days ago (June 25, 2024) Extended support release 115.12.0esr[2]  / June 11, 2024; 19 days ago (June 11, 2024)
Preview release(s) [±]
Beta & developer edition 128.0b8[3]  / June 26, 2024; 4 days ago (June 26, 2024) Nightly 129.0a1[4]  / June 10, 2024; 20 days ago (June 10, 2024)
Repository	hg.mozilla.org/mozilla-central/
Written in	C++, JavaScript, HTML, C, Rust, and others[5][6]
Engines	Gecko, Quantum, and SpiderMonkey; WebKit on iOS
Operating system	Linux macOS 10.15 or later Windows 10 or later Android 5.0 or later[7] iOS 15.0 or later
Included with	Various Unix-like operating systems
Available in	97 languages[8]
Type	Web browser
License	MPL 2.0[9][10]
Website	mozilla.org/firefox

Mozilla Firefox, or simply Firefox, is a free and open-source^[11] 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.^[12] Firefox is available for Windows 10 or later versions, macOS, and Linux. Its unofficial ports are available for various Unix and Unix-like operating systems, including FreeBSD,^[13] OpenBSD,^[14] NetBSD,^[15] and other platforms. It 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. An optimized version is also available on the Amazon Fire TV as one of the two main browsers available with Amazon's Silk Browser.^[16]

Firefox is the spiritual successor of Netscape Navigator, as the Mozilla community was created by Netscape in 1998, before its acquisition by AOL.^[17] 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,^[18] and challenged Internet Explorer's dominance with 60 million downloads within nine months.^[19] In November 2017, Firefox began incorporating new technology under the code name "Quantum" to promote parallelism and a more intuitive user interface.^[20]

Firefox usage share grew to a peak of 32.21% in November 2009,^[21] with Firefox 3.5 overtaking Internet Explorer 7, although not all versions of Internet Explorer as a whole;^[22][23] its usage then declined in competition with Google Chrome.^[21] As of December 2023^[update], according to StatCounter, it had a 6.7% usage share on traditional PCs (i.e. as a desktop browser), making it the fourth-most popular PC web browser after Google Chrome (62%), Safari (13%), and Microsoft Edge (11%).^[24][25]

History[edit]

The project began as an experimental branch of the Mozilla project by Dave Hyatt, Joe Hewitt, and Blake Ross. They believed the commercial requirements of Netscape's sponsorship and developer-driven feature creep compromised the utility of the Mozilla browser.^[26] To combat what they saw as the Mozilla Suite's software bloat, they created a standalone browser, with which they intended to replace the Mozilla Suite.^[27] Version 0.1 was released on September 23, 2002.^[28] On April 3, 2003, the Mozilla Organization announced that it planned to change its focus from the Mozilla Suite to Firefox and Thunderbird.^[29]

The Firefox project has undergone several name changes.^[30] 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"). Phoenix was renamed in 2003 due to a trademark claim from Phoenix Technologies. The replacement name, Firebird, provoked an intense response from the Firebird database software project.^[31][32] 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.^[33] The name Firefox was said to be derived from a nickname of the red panda,^[34] which became the mascot for the newly named project.^[35] For the abbreviation of Firefox, Mozilla prefers Fx or fx, although it is often abbreviated as FF.^[36]

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^[37] and The Wall Street Journal.^[38] 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 and Opera, Firefox was the first of these browsers to have achieved large-scale adoption.^{[citation needed]} Firefox attracted attention as an alternative to Internet Explorer, 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 component, and vulnerability to spyware and malware installation.^{[citation needed]} Microsoft responded by releasing Windows XP Service Pack 2, which added several important security features to Internet Explorer 6.^[39]

Version 1.0 of Firefox was released on November 9, 2004.^[40] 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.^[41]

Major redesigns of its graphical user interface occurred on versions 4.0 (Strata) in March 2011, 29.0 (Australis) in April 2014, 57.0 (Photon) in November 2017, and 89.0 (Proton) in June 2021.

In 2016, Mozilla announced a project known as Quantum, 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, 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 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.^[42][43][44] 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.^[45][46]

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).^[47][48] Mozilla began the roll-out of a fix shortly thereafter, using their Mozilla Studies component.^[47][48]

Support for Adobe Flash was dropped on January 6, 2021, with the release of Firefox 85. ^[49]

On June 1, 2021, Firefox's 'Proton' redesign was offered through its stable release channel^[50] after being made available in the beta builds.^[51] While users were initially allowed to revert to the old design through about:config, the corresponding key-value pairs reportedly stopped working in future builds, resulting in criticism.^[52] These included accessibility concerns^[53][54] despite Mozilla's claim to "continue to work with the accessibility community"^[55] and are continuing issues.^[56]

On January 13, 2022, an issue with Firefox's HTTP/3 implementation resulted in a widespread outage for multiple hours.^[57]

On September 26, 2023, Firefox 118.0 introduced on-device translation of web page content. ^[58]

On January 23, 2024, along with the release of Firefox 122.0, Mozilla introduced an official APT repository for Debian-based Linux distributions.^[59]

Features[edit]

Features of the desktop edition include tabbed browsing, full-screen mode, spell checking, incremental search, smart bookmarks, bookmarking and downloading through drag and drop,^[60][61] a download manager, user profile management,^[62] private browsing, bookmark tags, bookmark exporting,^[63] offline mode,^[64] a screenshot tool, web development tools, a "page info" feature which shows a list of page metadata and multimedia items,^[65] a configuration menu at about:config for power users, and location-aware browsing (also known as "geolocation") based on a Google service.^[66] Firefox has an integrated search system which uses Google by default in most markets.^[67][68] DNS over HTTPS is another feature whose default behaviour is determined geographically.^[69]

Firefox provides an environment for web developers in which they can use built-in tools, such as the Error Console or the DOM Inspector, and extensions, such as Firebug and more recently there has been an integration feature with Pocket. Firefox Hello was an implementation of WebRTC, 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.^[70]

Former features include a File Transfer Protocol (FTP) client for browsing file servers, the ability to block images from individual domains (until version 72),^[71] a 3D page inspector (versions 11 to 46), tab grouping (until version 44), and the ability to add customized extra toolbars (until version 28).^[72][73][74]

Browser extensions[edit]

Functions can be added through add-ons created by third-party developers. Add-ons are primarily coded using an HTML, CSS, JavaScript, with API known as WebExtensions, which is designed to be compatible with Google Chrome and Microsoft Edge extension systems.^[75] Firefox previously supported add-ons using the XUL and XPCOM 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.^[76][77]

Mozilla has occasionally installed extensions for users without their permission. This happened in 2017 when an extension designed to promote the show Mr. Robot was silently added in an update to Firefox.^[78][79]

Themes[edit]

Firefox can have themes added to it, which users can create or download from third parties to change the appearance of the browser.^[80][81]

Guest session[edit]

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".^[82][83]

Standards[edit]

Firefox implements many web standards, including HTML4 (almost full HTML5), XML, XHTML, MathML, SVG 1.1 (full),^[84] SVG 2 (partial),^[85][86] CSS (with extensions),^[87] ECMAScript (JavaScript), DOM, XSLT, XPath, and APNG (Animated PNG) images with alpha transparency.^[88] Firefox also implements standards proposals created by the WHATWG such as client-side storage,^[89][90] and the canvas element.^[91] These standards are implemented through the Gecko layout engine, and SpiderMonkey JavaScript engine. Firefox 4 was the first release to introduce significant HTML5 and CSS3 support.

Firefox has passed the Acid2 standards-compliance test since version 3.0.^[92] Mozilla had originally stated that they did not intend for Firefox to pass the Acid3 test fully because they believed that the SVG fonts part of the test had become outdated and irrelevant, due to WOFF being agreed upon as a standard by all major browser makers.^[93] Because the SVG font tests were removed from the Acid3 test in September 2011, Firefox 4 and greater scored 100/100.^[94][95]

Firefox also implements "Safe Browsing,"^[96] a proprietary protocol^[97] from Google used to exchange data related with phishing and malware protection.

Firefox supports the playback of video content protected by HTML5 Encrypted Media Extensions (EME), since version 38. For security and privacy reasons, EME is implemented within a wrapper of open-source code that allows execution of a proprietary DRM module by Adobe Systems—Adobe Primetime Content Decryption Module (CDM). CDM runs within a "sandbox" environment to limit its access to the system and provide it a randomized device ID to prevent services from uniquely identifying the device for tracking purposes. The DRM module, once it has been downloaded, is enabled, and disabled in the same manner as other plug-ins. Since version 47,^[98] "Google's Widevine CDM on Windows and Mac OS X so streaming services like Amazon Video can switch from Silverlight to encrypted HTML5 video" is also supported. Mozilla justified its partnership with Adobe and Google by stating:

Firefox downloads and enables the Adobe Primetime and Google Widevine CDMs by default to give users a smooth experience on sites that require DRM. Each CDM runs in a separate container called a sandbox and you will be notified when a CDM is in use. You can also disable each CDM and opt-out of future updates

— Watch DRM content on Firefox^[99]

and that it is "an important step on Mozilla's roadmap to remove NPAPI plugin support."^[100] Upon the introduction of EME support, builds of Firefox on Windows were also introduced that exclude support for EME.^[101][102] The Free Software Foundation and Cory Doctorow condemned Mozilla's decision to support EME.^[103]

Security[edit]

From its inception, Firefox was positioned as a security-focused browser. At the time, Internet Explorer, the dominant browser, was facing a security crisis. Multiple vulnerabilities had been found, and malware like Download.Ject could be installed simply by visiting a compromised website. The situation was so bad that the US Government issued a warning against using Internet Explorer.^[104] Firefox, being less integrated with the operating system, was considered a safer alternative since it was less likely to have issues that could completely compromise a computer. This led to a significant increase in Firefox's popularity during the early 2000s as more secure alternative.^[105][106] Moreover, Firefox was considered to have fewer actively exploitable security vulnerabilities compared to its competitors. In 2006, The Washington Post reported that exploit code for known security vulnerabilities in Internet Explorer were available for 284 days compared to only nine days for Firefox before the problem was fixed.^[107] A Symantec study around the same period showed that even though Firefox had a higher number of vulnerabilities, on average vulnerabilities were fixed faster in Firefox than in other browsers during that period.^[108]

During this period, Firefox used a monolithic architecture, like most browsers at the time. This meant all browser components ran in a single process with access to all system resources. This setup had multiple security issues. If a web page used too many resources, the entire Firefox process would hang or crash, affecting all tabs. Additionally, any exploit could easily access system resources, including user files. Between 2008 and 2012, most browsers shifted to a multiprocess architecture, isolating high-risk processes like rendering, media, GPU, and networking.^[109] However, Firefox was slower to adopt this change. It wasn't until 2015 that Firefox started its Electrolysis (e10s) project to implement sandboxing across multiple components. This rewrite relied on interprocess communication using Chromium's interprocess communication library and placed various component including the rendering component in its own sandbox.^[110] Firefox released this rewrite in to beta in August 2016, noting a 10-20% increase in memory usage, which was lower than Chrome's at the time.^[111] However, the rewrite caused issues with their legacy extension API, which was not designed to work cross-process and required shim code to function correctly.^[111] After over a year in beta, the rewrite was enabled by default all users of Firefox in November 2017.^[112]

In 2012, Mozilla launched a new project called Servo to write a completely new and experimental browser engine utilizing memory safe techniques written in Rust.^[113] In 2018, Mozilla opted to integrate parts of the Servo project into the Gecko engine in a project codenamed the Quantum project.^[114] The project completely overhauled Firefox's page rendering code resulting in performance and stability gains while also improving the security of existing components.^[115] Additionally, the older incompatible extension API was removed in favour of a WebExtension API that more