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Mozilla is a free, cross-platform Internet software suite, whose components include a web browser and an email client, HTML editor and IRC client. It is also the name of the open source project responsible for the development of this software.

Table of contents
1 Overview
2 History of Mozilla
3 Future development of the Mozilla platform
4 Mozilla technology
5 Origins and prophecies: the "Mozilla" name
6 Version History
7 Spin-off Browsers
8 External links


This article using Mozilla

The name Mozilla had been used internally for the web browser Netscape Navigator from its beginning. The name arose because Netscape Navigator was to be the successor to the web browser Mosaic and was a contraction of Mosaic-killer Godzilla. This name was not used externally, but references to it could be found in pictures of Godzilla associated with Netscape Navigator.

In February 1998, Netscape released most of the code base for its popular Netscape Communicator suite (including the Netscape Navigator browser) under an open source license. The name of the application developed from this would be Mozilla, co-ordinated by the newly-created Mozilla organization, at the website.

Although the original Communicator code was abandoned shortly thereafter, the Mozilla organization eventually succeeded in producing a full-featured Internet suite that surpassed Communicator in both features and stability.

Under the AOL banner, continued development of the browser and management of the Mozilla source until July 2003 when this task passed to The Mozilla Foundation. The Foundation is a non-profit organisation composed primarily of developers and staff from and owns all intellectual property related to Mozilla. It received initial donations from AOL, IBM, Sun Microsystems and Red Hat, however all official ties with AOL were severed following the announcement of the end of the Netscape Navigator browser and AOL's agreement to use Microsoft's Internet Explorer browser in future versions of its AOL software. (AOL has since announced it will be using Mozilla's Gecko layout engine.)

Like many other large software projects, Mozilla itself has become a platform for other programs and libraries written in its domain specific programming environment. Extensions vary widely in complexity, ranging from simple JavaScript-based bookmarklets, to Mozilla feature extensions (such as support for mouse gestures and pie menus), to full-fledged standalone programs. A partial list of programs and extensions for the Mozilla platform can be found on the website.

History of Mozilla

The Netscape Communicator open source release, which came at the height of America's late-1990s economic boom, was greeted by the Internet community with a mixture of acclaim and skepticism. In some circles, Netscape's source release was seen as both a victory for the free software movement and an opportunity for Netscape to tap the power of open source development. This view was particularly popular among users of Linux and other free software. Other observers—including many in the non-open-source business community—interpreted the move as Netscape's surrender in the face of the growing ascendancy of Microsoft's Internet Explorer browser.

Regardless of the public's opinion, development with the Communicator code base proved harder than initially hoped:

As a result, the initial Communicator open source release did not even build cleanly, much less run. This presented steep challenges to the Mozilla core developers (most of whom were still on Netscape's payroll), and even steeper challenges to independent developers wishing to contribute to Mozilla on their own.

Ultimately, the Mozilla core developers concluded that the old code could not be salvaged. They decided to scrap the whole code base and rewrite it from the ground up, which caused one of the lead Netscape developers, Jamie Zawinski, to resign. The resulting plan included, among other things, the creation of a whole new cross-platform user interface library and a new HTML rendering engine.

Few observers foresaw the result. The rapid completion of the Gecko HTML layout engine led many to believe that a complete browser could not be far behind. However, producing even a fully functional web browser required much more than a rendering engine; and the Mozilla developers soon envisioned a project more ambitious than a simple web browser. The new Mozilla would be a platform for Internet applications, with a fully programmable user interface and a modular architecture. This Mozilla would function equally well as a host for email clients, instant messaging clients, Usenet news readers, or any number of other applications.

Due to the effort required for this massive rewrite, the project fell far behind its original projected deadlines. In the years that followed, skepticism about Mozilla grew widespread, and some doubted that a finished Mozilla browser would ever see the light of day. However, the project persisted, continuing uninterrupted through both the purchase of Netscape by AOL and the end of the dot-com boom.

By 2002, the Mozilla project had produced a serviceable, standards-based web browser that worked on multiple operating systems, including Linux, Mac OS, Solaris, and Microsoft Windows. The Mozilla 1.0 release was even praised for introducing new features that Internet Explorer lacked, including better support for user privacy preferences and some interface improvements. Additionally, the Mozilla browser became a de facto reference implementation for various World Wide Web Consortium standards, due to its strong support for those standards. Current versions of Mozilla are highly customisable and include advanced features such as cookie, popup, password and image management and tabbed browsing.

On July 15th 2003, AOL announced that it would axe off its browser division, which was in essence, Netscape's Mozilla. Far from being the end, this was the beginning of the Mozilla Foundation, formed by former Netscape/Mozilla veterans to take responsibility of the development of Mozilla. As a consolation AOL pledged $2 million to help the new formed foundation.

Many people had been expecting this, after AOL reached a settlement with competitior, Microsoft, with a deal for the AOL software to use Internet Explorer for the next 7 years. Netscape had always been seen as a bargaining chip for AOL against Microsoft.

AOL laid off most of Netscape's employees and hackers, except for some who were transferred to other divisions. Netscape signs were seen being pulled off its building, confirming what many took as the end of Netscape. AOL will be keeping the Netscape brand for its portal, but all new Netscape browser development is expected to cease, with the last major version being 7.1 (based on mozilla 1.4).

Mozilla, a product originally aimed at developers instead of end users, now faces the challenge of marketing to the masses.

Future development of the Mozilla platform

A new development roadmap has been released which marks a change in the future plans for Mozilla. Instead of the current integrated "cross-platform front end" (XPFE) application, Mozilla will become a suite of smaller applications sharing common back-end technology such as the XUL user-interface framework and the Gecko rendering engine. They will continue to work seamlessly with one another, as before, but will be able to integrate better with third-party applications. By cutting the functionality of the suite into pieces, this is intended to improve the project in several ways, by

This is not a long-term goal: the Firebird (formerly Phoenix) browser is already in an advanced state of development, and the Thunderbird (formerly Minotaur) mail client is in the early stages of being factored out from XPFE.

Mozilla technology


The Mozilla software architecture was, of necessity, fairly modular. As a result, Mozilla development generated several components that have been reused in other contexts. The most prominent of these is the Gecko layout engine, which has been used in other browsers (see Spin-off browsers below).

Also, the task of Mozilla development itself spurred the creation of tools for geographically distributed, cross-platform software development. Some of these tools were widely adopted by the larger open source community, including the following:

Notable features of Mozilla's design

One unique aspect of Mozilla is that the entire user interface, including menus and dialog boxes, is rendered by the Gecko layout engine, rather than by the host operating system's GUI library. This architecture has been controversial. Its defenders cite its flexibility and the fact that it can present a standard GUI across different platforms. Its critics argue that this architecture adversely impacts performance, and that it is a widely-accepted convention of application design to use the native GUI elements of the operating system interface. A number of browsers exist that use the rendering engine only to display the HTML page (see below).

Origins and prophecies: the "Mozilla" name

The Mozilla project takes its name from the cartoon lizard Mozilla, who served as Netscape's mascot in the company's early days. The name is a portmanteau of "Mosaic" (the Netscape browser's predecessor) and "Godzilla" (a movie monster that terrorized Tokyo and other locales). One can surmise that the employees of Netscape hoped to unseat Mosaic as the web's most popular browser. They succeeded---albeit briefly, yielding the position to Internet Explorer soon after. For more on the Mozilla mascot, see the external link for "The Mozilla Museum" (below).

When given the URL about:mozilla, the various versions of the Netscape browser would display a message, in white text on a lurid red background, in the browser window. Versions 1 to 4 displayed the following prophecy:

And the beast shall come forth surrounded by a roiling cloud of vengeance.
The house of the unbelievers shall be razed and they shall be scorched to the earth. Their tags shall blink until the end of days.
from The Book of Mozilla, 12:10

"Their tags shall blink" refers to the controversial <blink> HTML tag introduced in an earlier Netscape version. This proprietary HTML extension, which made text blink on and off, was widely derided as annoying, distracting, and ugly. Soon after its introduction, the blink tag joined hideously garish backgrounds and animated GIFs as metonymy for badly designed web pages. The numbers 12:10 refer to the release date of Netscape 1.0, December 10, 1994.

Later Netscape browser versions (as well as the Mozilla browser itself), which were actually based on the Mozilla code, displayed the following:

And the beast shall be made legion. Its numbers shall be increased a thousand thousand fold. The din of a million keyboards like unto a great storm shall cover the earth, and the followers of Mammon shall tremble.
from The Book of Mozilla, 3:31
(Red Letter Edition)

This text probably referred to Netscape's hope that, by opening the Mozilla source, they could attract a "legion" of developers who would help improve the software. Some suggested that "Mammon" referred obliquely to Microsoft, which seemed plausible given that Microsoft's Internet Explorer was Mozilla's chief competition. The numbers 3:31 refer to March 31 1998, the date which Netscape 5.0 was made open source.

The next installment (7:15) is said to be written by Neil Deakin, to mark the establishment of the Mozilla Foundation, which cuts Mozilla loose from its parent company Netscape/AOL. Moreover it hints at the separation of the browser (Firebird) and the mail-client (Thunderbird). This is a reference to the name "Phoenix," which was what Mozilla Firebird was called before the name was changed to avoid copyright difficulty.

And so at last the beast fell and the unbelievers rejoiced. But all was not lost, for from the ash rose a great bird. The bird gazed down upon the unbelievers and cast fire and thunder upon them. For the beast had been reborn with its strength renewed, and the followers of Mammon cowered in horror.
from The Book of Mozilla, 7:15
(Red Letter Edition)

Version History

Early versions of Mozilla were slow and buggy. Mozilla became about as stable as Netscape 4.7x only from 0.9.2 or 0.9.3 builds onwards. From 0.9.5 (October 12, 2001) onwards the releases have been fast and reliable, largely due to the implementation of formal code review techniques by the Mozilla project managers.

VersionRelease dateMost important changes
Milestone 1December 10, 1998(a.k.a. Gecko Developer Release) Conversion to the "raptor" codebase; about 100 bugfixes
Milestone 2January 31, 1999Platform parity (Windows / Linux / MacOS); about 85 bugfixes
Milestone 3March 19, 1999Simple Sidebar, Preferences
Milestone 4April 15, 1999Minimal Profile, Mac Mail, IMAP
Milestone 5May 5, 1999Component Jar Installers, XPConnect
Milestone 6May 29, 1999Componentization, History
Milestone 7June 22, 1999Necko Phase 1
Milestone 8July 16, 1999Necko, XP Toolkit
Milestone 9August 26, 1999Necko Landing and Recovery
Milestone 10October 8, 1999Continued Feature Work, Performance and Stability
Milestone 11November 16, 1999Space and time analysis and optimizations
Milestone 12December 21, 1999Performance, Stabilization
Milestone 13January 26, 2000(a.k.a. Mozilla Alpha Release) Archechtural Landings, Feature Work
Milestone 14March 1, 2000Focus on Clean up and Stability
Milestone 15April 18, 2000Crypto Landed, Webshell Update Landed, Skinable UI, Other Architectural work
Milestone 16June 13, 2000Autocomplete, Chatzilla, HTTP/1.1 support, skin support, full session history support
Milestone 17August 7, 2000Classic theme, alpha transparency, MNG support, plugin support on Linux
Milestone 18October 12, 2000Java support on Linux, Modern theme
Mozilla 0.6December 6, 2000source-only release of the base for Netscape 6.0
Mozilla 0.7January 9, 2001Personal security manager; SSL and mousewheel support on MacOS; forced reloads from server
Mozilla 0.8February 14, 2001Find and replace; first introduction of pop-up blocking; improved bookmark manager
Mozilla 0.8.1March 26, 2001Improved Chatzilla and Javascript Console; initial gopher support
Mozilla 0.9May 7, 2001Automatic proxy configuration; personal security manager 2.0; performance improvements
Mozilla 0.9.1June 7, 200134 crasher bugs fixed; overhauled Modern theme; XSLT support; bidi support for Hebrew and Arabic
Mozilla 0.9.2June 28, 200125 crasher bugs fixed; Quick Launch (preloading to reduce startup times) implemented on Windows
Mozilla 0.9.3August 2, 2001More stability work (Mozilla is now considered more stable than Netscape 4.78)
Mozilla 8, 2001source-only release of the base for Netscape 6.1
Mozilla 0.9.4September 14, 2001Quick Launch enabled by default; Arabic language support on Linux
Mozilla 0.9.5October 12, 2001Tabbed Browsing; SOCKS support for almost all protocols; ECMAScript debugger Venkman
Mozilla 0.9.6November 20, 2001Page icons displayed in toolbar (except for favicons); print preview; BMP and ICO support on all platforms
Mozilla 31, 2001source-only release of the base for Netscape 6.2
Mozilla 0.9.7December 21, 2001Favicon support.
Mozilla 0.9.8February 4, 2002Hebrew support on Solaris; Hebrew and Arabic support on MacOS; Document Object Model inspector
Mozilla 0.9.9March 11, 2002a new mail notification sign that appears in the Windows System tray.
Mozilla 1.0 RC1April 18, 2002Viewing source of cgi generated pages works, reorganized menus, new Download Manager
Mozilla 1.0 RC2May 10, 2002 
Mozilla 1.0 RC3May 23, 2002139 bug fixes since RC2.
Mozilla 1.0June 5, 2002first 'official' release
Mozilla 1.1August 26, 2002performance, stability, compatibility and standards conformance improved
Mozilla 1.0.1September 10, 2002over 650 bugfixes to 1.0.
Mozilla 1.2November 26, 2002type ahead find, improved keyboard access, link prefetching
Mozilla 1.2.1December 2, 2002released to correct a DHTML bug found in Mozilla 1.2
Mozilla 1.0.2January 7, 2003stability and security improvements and fixes for standards support
Mozilla 1.3March 13, 2003basic junk mail classification capabilities and image auto sizing
Mozilla 1.3.1May 7, 2003released to restore XPI functionality on Mac OS X
Mozilla 1.4bMay 7, 2003 
Mozilla 1.4 RC1May 29, 2003more junk mail controls, smooth scrolling, bookmarks overhaul, streamlined pop-up blocking
Mozilla 1.4 RC2June 17, 2003Lots of bug fixes.
Mozilla 1.4 RC3June 24, 2003More bug fixes.
Mozilla 1.4June 30, 2003Official 1.4 release.
Mozilla 1.4.1October 12, 2003About 100 bug fixes, spell checker.
Mozilla 1.5aJuly 22, 2003Composer improvements. MNG support removed.
Mozilla 1.5bAugust 27, 2003Spellchecker for Mail/News and Composer, Color support for <HR> tags
Mozilla 1.5October 15, 2003
Mozilla 1.6aOctober 31, 2003Mail enhancements, about:about feature
Mozilla 1.6bDecember 9, 2003

Early reviews of Mozilla 1.0 were favorable, describing Mozilla as fast and stable, and praising new features such as tabbed browsing and pop-up blocking.

One advanced setting which is highly beneficial to users of Mozilla is the ability to use the pipelining feature of HTTP 1.1, which results in much faster download times for sites with multiple images.

Spin-off Browsers

Browsers that use the Gecko layout engine for the entire user interface

Browsers that use the Gecko layout engine for webpage display only

Other projects based on Mozilla code

External links