Mozilla Firefox is a web browser descended from the Mozilla Application
Suite and managed by Mozilla Corporation. Official versions are distributed
under the terms of a proprietary EULA.
Firefox had 22.48% of the recorded usage share of web browsers as of April 2009,
making it the second most popular browser in terms of current use worldwide,
after Internet Explorer.
To display web pages, Firefox uses the Gecko layout engine, which implements
some current web standards in addition to a few features which are intended to
anticipate likely additions to the standards.
Firefox features include tabbed browsing, a spell checker, incremental find,
live bookmarking, a download manager, and an integrated search system that uses
the user's desired search engine (Google by default in most localizations).
Functions can be added through add-ons, created by third-party developers,
of which there is a wide selection, a fact which has attracted many of Firefox's
Tab Mix Plus customizer, FoxyTunes media player control toolbar, Adblock Plus ad
blocking utility, StumbleUpon (website discovery), Xmarks (bookmark
synchronizer), WOT: Web of Trust security site advisor, DownThemAll! download
enhancer, and Web Developer toolbar.
Firefox runs on various versions of Linux, Mac OS X, Microsoft Windows, and
many other Unix-like operating systems. Its current stable release is version
3.0.10, released on April 27, 2009.
Firefox's source code is free software, released under a tri-license GNU GPL/GNU
The Firefox project began as an experimental branch of the Mozilla project by
Dave Hyatt and Blake Ross. They believed the commercial requirements of
Netscape's sponsorship and developer-driven feature creep compromised the
utility of the Mozilla browser.
To combat what they saw as the Mozilla Suite's software bloat, they created a
stand-alone browser, with which they intended to replace the Mozilla Suite. On
April 3, 2003, the Mozilla Organization announced that they planned to change
their focus from the Mozilla Suite to Firefox and Thunderbird.
The Firefox project has undergone several name changes. Originally titled
Phoenix, it was renamed because of trademark issues with Phoenix
Technologies. The replacement name, Firebird, provoked an intense
response from the Firebird free database software project.
In response, the Mozilla Foundation stated that the browser should always bear
the name Mozilla Firebird to avoid confusion with the database software.
Continuing pressure from the database server's development community forced
another change; on February 9, 2004, Mozilla Firebird became Mozilla Firefox,
often referred to as simply Firefox. Mozilla prefers that Firefox be
abbreviated as Fx or fx, though it is often abbreviated as FF.
The Firefox project went through many versions before 1.0 was released on
November 9, 2004. After a series of stability and security fixes, the Mozilla
Foundation released its first major update, Firefox version 1.5, on November 29,
2005. On October 24, 2006, Mozilla released Firefox 2. This version includes
updates to the tabbed browsing environment; the extensions manager; the GUI; and
the find, search and software update engines; a new session restore feature;
inline spell checking; and an anti-phishing feature which was implemented by
Google as an extension,
and later merged into the program itself.
In December 2007, Firefox Live Chat was launched. It allows users to ask
volunteers questions through a system powered by Jive Software, with guaranteed
hours of operation and the possibility of help after hours.
Mozilla Firefox 3 was released on June 17, 2008
by the Mozilla Corporation. Firefox 3 uses version 1.9 of the Mozilla Gecko
layout engine for displaying web pages. The new version fixes many bugs,
improves standard compliance, and implements new web APIs.
Other new features include a redesigned download manager, a new "Places" system
for storing bookmarks and history, and separate themes for different operating
systems. The current version is Firefox 3.0.10. Development stretches back to
the first Firefox 3 beta (under the codename 'Gran Paradiso')
which had been released several months earlier on 19 November 2007,
and was followed by several more beta releases in spring 2008 culminating in the
June release. Firefox 3 had
over 8 million unique downloads the day it was released, setting a Guinness
The precursory builds of upcoming Firefox releases are usually codenamed
"Minefield", as this is the name of the trunk builds. Pre-release versions for
Firefox 3.5 (based on the Mozilla 1.9.1 branch) are also available. Development
on the Mozilla trunk (mozilla-central) is currently directed towards the Version
After three initial beta releases under the Firefox 3.1 moniker, Mozilla
developers decided to change the numbering of the upcoming release to 3.5, in
order to reflect a significantly greater scope of changes than originally had
Version 3.5, codenamed Shiretoko,
is planned to include support for the
tags as defined in the HTML 5 specification. The goal of Firefox's open-source
in-browser video is to offer video playback without being encumbered by patent
issues associated with so many video technologies.
Cross-site XMLHttpRequests (XHR), which would allow for more powerful web
applications and an easier way to implement mashups, is also in planning. Native
JSON DOM binding, a powerful feature for web developers, may also be included,
together with full CSS 3 selector support.
Firefox 3.5 will use the Gecko 1.9.1 engine, which includes a few features that
were not included in the 3.0 release. Multi-touch support will also be added to
the release, including gesture support like pinching for zooming, swiping for
back and forward and twisting for changing the tab.
The Alpha 1 was released in late July 2008.
Alpha 2 was launched on September 6, 2008, adding new video support. TraceMonkey
and Beta 2 on December 8, 2008.
Beta 2 includes a Private Browsing feature which, when active, does not store
any data revealing a user's visited sites on the hard drive.
Beta 3 was released on March 12, 2009.
 Beta 4, the first
to be labeled as version 3.5 was released on April 27, 2009.
Version 3.5 will also change the default search engine in Russian language
builds, using the popular Russian search engine Yandex rather than Google after
a survey of Russian Firefox users indicated they preferred Yandex.
The release that will follow Firefox 3.5 (previously known as Firefox 3.1) is
referred to as 3.6 ad interim
(and was originally referred to as 3.2). The codename for this version has been
set to Namoroka. The release
date is not yet known. Development started on 1 December 2008.
This release will use the Gecko 1.9.2 engine on the Mozilla 2 platform and
include several interface improvements, such as new graphical tab-switching
behaviour, which was removed from 3.1 Beta 2.
On October 13, 2006, Brendan Eich, Mozilla's Chief Technology Officer, wrote
about the plans for Mozilla 2, the platform on which Firefox 4.0 is likely to be
based. These changes include improving and removing XPCOM APIs, switching to
Tamarin project), and tool-time and runtime security checks.
It has also been announced that support for the Gopher protocol will be removed
by default to lessen attack vectors, but it has also been suggested that the
protocol could be retained if someone were to implement Gopher support in a
memory-safe programming language.
And as well as support for x64bit Window Operating Systems.
Mitchell Baker, Mozilla's former Chief Executive Officer, has spoken of the
Mozilla Foundation's plans to create a version of Firefox, codenamed Fennec,
that will run reliably on mobile phones, as well as a strategy for syncing
content downloaded on a PC with mobile handsets.
Meanwhile, integral offline application support technology—similar to
Gears—is also being developed for Firefox. Baker has said that given the level
of investment made in the web as a platform, taking applications to the next
level will require that they continue to work when a computer is offline.
Features included with Firefox are tabbed browsing, spell checker,
incremental find, live bookmarking, an integrated download manager, keyboard
shortcuts, and an integrated search system that uses the user's desired search
Users can customize Firefox with browser "add-ons". Mozilla maintains a
repository of these developed extensions and themes at addons.mozilla.org with
nearly 6,500 available as of December 2008.
Firefox provides an environment for web developers in which they can use
built-in tools, such as the Error Console or the DOM Inspector, or extensions,
such as Firebug.
Mozilla Firefox implements many web standards, including HTML, XML, XHTML,
MathML, SVG 1.1 (partial), CSS
(with extensions), ECMAScript
transparency. Firefox also
implements standards proposals created by the WHATWG such as client-side
and canvas element.
Firefox passes the Acid2 standards-compliance test from version 3.0.
Like all other stable browsers as of January 2009 ,
Firefox 3.0 does not pass the Acid3 test; it scores 71/100 and does not render
the image correctly. Firefox 3.6 alpha scores 94/100, renders the image
correctly except for the wrong favicon. It does not pass the performance aspect
of Acid3 either.
Firefox uses an open source implementation of a protocol acquired from Google
called "safebrowsing" (used to exchange data related with "phishing and malware
protection"), which was developed by Google and based on a proprietary standard.
Firefox uses a sandbox security model,
and limits scripts from accessing data from other web sites based on the same
origin policy. It uses SSL/TLS
to protect communications with web servers using strong cryptography when using
the https protocol. It also
provides support for web applications to use smartcards for authentication
The Mozilla Foundation offers a "bug bounty" to researchers who discover
severe security holes in Firefox.
Official guidelines for handling security vulnerabilities discourage early
disclosure of vulnerabilities so as not to give potential attackers an advantage
in creating exploits.
Because Firefox has fewer and less severe publicly known unpatched security
vulnerabilities than Internet Explorer (see Comparison of web browsers),
improved security is often cited as a reason to switch from Internet Explorer to
The Washington Post reports that exploit code for critical unpatched
security vulnerabilities in Internet Explorer was available for 284 days in
2006. In comparison, exploit code for critical security vulnerabilities in
Firefox was available for 9 days before Mozilla shipped a patch to remedy the
A 2006 Symantec study showed that although Firefox had surpassed other
browsers in the number of vendor-confirmed vulnerabilities that year through
September, these vulnerabilities were patched far more quickly than those found
in other browsers. Symantec
later clarified their statement, saying that Firefox still had fewer security
vulnerabilities than Internet Explorer, as counted by security researchers.
As of April 23, 2009, Firefox 3 has no security vulnerabilities unpatched
according to Secunia. Internet
Explorer 7 has nine security vulnerabilities unpatched, the most severe of which
was rated "moderately critical" by Secunia.
System and hardware requirements
Browsers compiled from Firefox source code may run on various operating
systems, however officially distributed binaries are meant for: Microsoft
Windows (Windows 2000, Windows XP, Windows Server 2003 or Windows Vista), Mac OS
X 10.4 (or later) and Linux (with the following libraries installed: GTK+ 2.10
or higher, GLib 2.12 or higher, Pango 1.14 or higher, X.Org 1.0 or higher *or
any TinyX server implementation*). Official minimum hardware requirements are
Pentium 233 MHz and 64 MB RAM for Windows version or Macintosh computer with an
Intel x86 or PowerPC G3, G4, or G5 processor and 128 MB RAM for Mac version.
64 bit compatibility
Firefox currently does not support 64 bit operating systems. An alternative
to this is to use the 'MineField' build.
Windows x64 based platforms are not compatible with Firefox as of now, however
Firefox may be installed on Vista x64 and will run in the x86 compatibility
layer. Linux based operating systems however can run 32 bit and 64 bit binaries.
Firefox source code is free and open source software, and is tri-licensed
under the Mozilla Public License (MPL), GNU General Public License (GPL), and
the GNU Lesser General Public License (LGPL).
These licenses permit anyone to view, modify and/or redistribute the source
code, and several publicly released applications have been built on it; for
example, Netscape, Flock, Miro, Iceweasel, and Songbird make use of code from
The official end-user builds of Firefox distributed from mozilla.com are
licensed under the Mozilla End User License Agreement (EULA).
Several elements do not fall under the scope of the tri-license and have their
use restricted by the EULA, including the trademarked Firefox name, the
proprietary artwork, and the proprietary closed-source Talkback crash reporter
in Firefox version prior to 3. Because of this and the clickwrap agreement
included in the Windows version, the Free Software Foundation (FSF) consider
these builds proprietary software.
However, BreakPad, an open source crash reporting system, has replaced Talkback
in Firefox 3.0.
In the past, Firefox was licensed solely under the MPL,
which the FSF criticizes for being weak copyleft; the license permits, in
limited ways, proprietary derivative works. Additionally, code under the MPL
cannot legally be linked with code under the GPL or the LGPL.
To address these concerns, Mozilla re-licensed Firefox under the tri-license
scheme of MPL, GPL, and LGPL. Since the re-licensing, developers have been free
to choose the license under which they will receive the code, to suit their
intended use: GPL or LGPL linking and derivative works when one of those
licenses is chosen, or MPL use (including the possibility of proprietary
derivative works) if they choose the MPL.
Trademark and logo issues
The name "Mozilla Firefox" is a registered trademark; along with the official
Firefox logo, it may only be used under certain terms and conditions. Anyone may
redistribute the official binaries in unmodified form and use the Firefox name
and branding for such distribution, but restrictions are placed on distributions
which modify the underlying source code.
Mozilla not only forbids creating derivative works from Firefox logo (i.e.
but also strongly discourages creating independent, but similar logos.
There has been some controversy over the Mozilla Foundation's intentions in
stopping certain open source distributions from using the "Firefox" trademark.
Former Mozilla CEO Mitchell Baker explained in an interview in 2007 that
distributions could freely use the Firefox trademark if they did not modify
source-code, and that the Mozilla Foundation's only concern was with users
getting a consistent experience when they used "Firefox".
To allow distributions of the code without using the official
branding, the Firefox source code contains a "branding switch". This switch
allows the code to be compiled without the official logo and name, for example
to produce a derivative work unencumbered by restrictions on the Firefox
trademark (this is also often used for alphas of future Firefox versions). In
the unbranded compilation the trademarked logo and name are replaced with a
freely distributable generic globe logo and the name of the release series from
which the modified version was derived. The name "Deer Park" is used for
derivatives of Firefox 1.5, "Bon Echo" for derivatives of Firefox 2.0, and "Gran
Paradiso" is used for derivatives of Firefox 3.0. The codename Minefield and a
modified version of the generic logo stylized to look like a bomb is used for
unofficial builds of version 3.0 and later, and for nightly builds of the trunk.
Distributing modified versions of Firefox under the "Firefox" name requires
explicit approval from Mozilla for the changes made to the underlying code, and
requires the use of all of the official branding. For example, it is not
permissible to use the name "Firefox" without also using the official logo. When
the Debian project decided to stop using the official Firefox logo in 2006
(because of copyright restrictions on its use incompatible with the project's
guidelines), they were told by a representative of the Mozilla Foundation that
this was not acceptable, and were asked either to comply with the published
trademark guidelines or cease using the "Firefox" name in their distribution.
Ultimately, Debian switched to branding their modified version of Firefox "Iceweasel",
along with other Mozilla software.
The rapid adoption of Firefox, 100 million downloads in its first year of
availability, followed a
series of aggressive marketing campaigns starting in 2004 with a series of
events Blake Ross and Asa Dotzler called "marketing weeks".
On September 12, 2004, a
marketing portal dubbed "Spread Firefox" (SFX) debuted along with the Firefox
Preview Release, creating a centralized space for the discussion of various
marketing techniques. The portal enhanced the "Get Firefox" button program,
giving users "referrer points" as an incentive. The site lists the top 250
referrers. From time to time, the SFX team or SFX members launch marketing
events organized at the Spread Firefox website. As a part of the Spread Firefox
campaign, there is an attempt to break the world download record with the
release of Firefox 3. The idea is to have the newest version downloaded by as
many people as possible within a 24 hour time period.
The "World Firefox Day" campaign started on July 15, 2006,
the third anniversary of the founding of the Mozilla Foundation,
and ran until September 15, 2006.
Participants registered themselves and a friend on the website for nomination to
have their names displayed on the Firefox Friends Wall, a digital wall that will
be displayed at the headquarters of the Mozilla Foundation.
On February 21, 2008 in honour of reaching 500 million downloads, the Firefox
community celebrated by visiting FreeRice to earn 500 million grains of rice.
Firefox usage share by version
— NetApplications.com, April 2009
Mozilla Firefox's usage share has grown for each growth period since
inception, mostly at the expense of Internet Explorer; Internet Explorer has
seen a steady decline of its usage share since Firefox's release. As of March
according to NetApplications, Firefox had 22.48% worldwide usage share of web
browsers, making it the second most-used browser, after Internet Explorer.
Downloads have continued at an increasing rate since Firefox 1.0 was released
in November 2004, and as of November 3, 2008 Firefox has been downloaded over
700 million 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. According to Mozilla, Firefox had more than
220 million users as of January 2009 .
Forbes.com called Firefox the best browser in a 2004 commentary piece,
and PC World named Firefox "Product of the Year" in 2005 on their "100
Best Products of 2005" list.
After the release of Firefox 2 and Internet Explorer 7 in 2006, PC World
reviewed both and declared that Firefox was the better browser.
Which? Magazine named Firefox its "Best Buy" web browser.
In 2008, CNET.com compared Safari, Chrome, Firefox, and Internet Explorer in
their "Battle of the Browsers" in terms of performance, security, and features,
where Firefox was selected as a favorite.
In December 2005 Internet Week ran an article in which many readers
reported high memory usage in Firefox 1.5.
Mozilla developers said that the higher memory use of Firefox 1.5 was at least
partially due to the new fast backwards-and-forwards (FastBack) feature.
Other known causes of memory problems were malfunctioning extensions such as
Google Toolbar and some older versions of Adblock,
or plug-ins, such as older versions of Adobe Acrobat Reader.
When PC Magazine compared memory usage of Firefox, Opera and Internet
Explorer, they found that Firefox used approximately as much memory as the other
Softpedia also noted that Firefox 1.5 took longer to start up than other
browsers, which was
confirmed by browser speed tests. IE 6 launches faster than Firefox 1.5 on
Microsoft Windows since many of its components are built into Windows and are
loaded during system startup. As a workaround for the issue, a preloader
application was created that loads components of Firefox on startup, similar to
Internet Explorer. A Windows
Vista feature called SuperFetch performs a similar task of preloading Firefox if
it is used often enough.
Tests performed by PC World and Zimbra indicate that Firefox 2 uses
less memory than Internet Explorer 7.
Firefox 3 uses less memory than Internet Explorer, Opera, Safari, and Firefox 2
in tests performed by Mozilla, CyberNet, and The Browser World.
Relationship with Google
The Mozilla Corporation's relationship with Google has been noted in the
especially with regard to their paid referral agreement. The release of the
anti-phishing protection in Firefox 2 in particular raised considerable
protection enabled by default is based on a list updated by twice-hourly
downloads to the user's computer from Google's server.
The user cannot change the data provider within the GUI,
and is not informed who the default data provider is. The browser also sends
Google's cookie with each update request.
An additional, explicitly opt-in security feature has been added to recent
builds by the Mozilla Foundation. This anti-phishing feature provides live
protection by checking each visited URL with Google.
Some Internet privacy advocacy groups have expressed concerns surrounding
states that Google may share information gathered with "safebrowsing" service
with third parties, including business partners.
In 2005, the Mozilla Foundation and Mozilla Corporation had a combined
revenue of US$52.9 million, with approximately 95 percent derived from search
In 2006, the Mozilla Foundation and Mozilla Corporation had a combined revenue
of US$66.9 million, with approximately 90 percent derived from search engine
In 2007, the Mozilla Foundation and Mozilla Corporation had a combined revenue
of US$75 million, with 88 percent of this sum (US$66 million) from Google.
Mozilla Foundation is being audited by the IRS and some believe its non-profit
status may be called into question.
Response from Microsoft
Microsoft's head of Australian operations, Steve Vamos, stated in late 2004
that he did not see Firefox as a threat and that there was not significant
demand for the feature set of Firefox among Microsoft's users.
Microsoft Chairman Bill Gates has used Firefox, but has commented that "so much
software gets downloaded all the time, but do people actually use it?"
A Microsoft SEC filing on June 30, 2005 acknowledged that "competitors such
as Mozilla offer software that competes with the Internet Explorer Web browsing
capabilities of our Windows operating system products."
The release of Internet Explorer 7 was fast tracked, and included functionality
that was previously available in Firefox and other browsers, such as tabbed
browsing and RSS feeds.
Despite the cold reception from Microsoft's top management, the Internet
Explorer development team maintains a relationship with Mozilla. They meet
regularly to discuss web standards such as extended validation certificates.
In 2005 Mozilla agreed to allow Microsoft to use its Web feed logo in the
interest of common graphical representation of the Web feeds feature.
In August 2006, Microsoft offered to help Mozilla integrate Firefox with the
then-forthcoming Windows Vista,
which Mozilla accepted.
In October 2006, as congratulations for a successful ship of Firefox 2, the
Internet Explorer 7 development team sent a cake to Mozilla.
As a nod to the browser wars, some readers joked about the cake being poisoned,
while others jokingly suggested that Mozilla send a cake back along with the
recipe, in reference to the open-source software movement.
The IE development team sent another cake on June 17, 2008, upon the successful
release of Firefox 3.
In November 2007, Microsoft employee Jeff Jones criticized Firefox, claiming
that Internet Explorer experienced fewer vulnerabilities and fewer higher
severity vulnerabilities than Firefox in typical enterprise scenarios.
Mozilla developer Mike Shaver discounted the study, citing Microsoft's bundling
of security fixes and the study's focus on fixes, rather than vulnerabilities,
as crucial flaws.
Firefox security vulnerabilities have been patched relatively quickly.
Symantec's Internet Security Threat Report Vol. 10, based on data from the first
half of 2006, reported that while Firefox had more vulnerabilities than Internet
Explorer during that time period (47 vs. 38), Firefox's vulnerabilities were
fixed on average one day after the exploit code was made available, as compared
to nine days for Internet Explorer.
Some have speculated that as Firefox becomes more popular, more
vulnerabilities will be found,
a claim that Mitchell Baker, president of the Mozilla Foundation, has denied:
"There is this idea that market share alone will make you have more
vulnerabilities. It is not relational at all."
Expert and media coverage
The United States Computer Emergency Readiness Team (US-CERT) stated in Oct
2004 that Internet Explorer's design makes it very difficult to secure. In
contrast, almost none of their concerns apply to Firefox.
There are a number of significant vulnerabilities in technologies
relating to the IE domain/zone security model, local file system (Local
Machine Zone) trust, the Dynamic HTML (DHTML) document object model (in
particular, proprietary DHTML features), the HTML Help system, MIME type
determination, the graphical user interface (GUI), and ActiveX… IE is
integrated into Windows to such an extent that vulnerabilities in IE
frequently provide an attacker significant access to the operating system.
Some security experts, including Bruce Schneier
and David A. Wheeler,
recommended that users should stop using Internet Explorer for normal browsing,
and switch to a different browser instead; Wheeler specifically recommended
Several technology columnists have suggested the same, including Wall
Street Journal columnist Walter S. Mossberg,
Washington Post columnist Rob Pegoraro,
USA Today’s Byron Acohido and Jon Swartz,
Forbes's Arik Hesseldahl,
eWEEK.com Senior Editor Steven J. Vaughan-Nichols,
and Desktop Pipeline’s Scot Finnie.
Mozilla Firefox has been given a number of awards by various organizations.
These awards include:
- PC Magazine Editors' Choice, June 2008
- CNET Editors' Choice, June 2008
- PC World 100 Best Products of 2008, May 2008
- Webware 100 winner, April 2008
- Webware 100 winner, June 2007
- PC World 100 Best Products of 2007, May 2007
- PC Magazine Editors' Choice, October 2006
- CNET Editors' Choice, October 2006
- PC World's 100 Best Products of 2006, July 2006
- PC Magazine Technical Excellence Award, Software and Development Tools
category, January 2006
- PC Magazine Best of the Year Award, December 27, 2005
- PC Pro Real World Award (Mozilla Foundation), December 8, 2005
- CNET Editors' Choice, November 2005
- UK Usability Professionals' Association Award Best Software Application
2005, November 2005
- Macworld Editor's Choice with a 4.5 Mice Rating, November 2005
- Softpedia User’s Choice Award, September 2005
- TUX 2005 Readers' Choice Award, September 2005
- PC World Product of the Year, June 2005
- Forbes Best of the Web, May 2005
- PC Magazine Editor’s Choice Award, May 2005
Cheah, Chu Yeow (2005). Firefox Secrets: A Need-To-Know Guide.
O'Reilly. ISBN 0-9752402-4-2.
Feldt, Kenneth C. (2007). Programming Firefox. O'Reilly. ISBN
Granneman, Scott (2005). Don't Click on the Blue e!: Switching to
Firefox. O'Reilly. ISBN 0-596-00939-9.
Hofmann, Chris; Marcia Knous, & John Hedtke (2005). Firefox and
Thunderbird Garage. Prentice Hall PTR. ISBN 0-13-187004-1.
McFarlane, Nigel (2005). Firefox Hacks. O'Reilly. ISBN
Reyes, Mel (2005). Hacking Firefox: More Than 150 Hacks, Mods, and
Customizations. Wiley. ISBN 0-7645-9650-0.
Ross, Blake (2006). Firefox for Dummies. Wiley. ISBN
The King, the Queen, the Emperor AND the
President of all web browsers
I just Love you, you Foxy thing