The Firefox Two browser made available for download on Tuesday was heralded by the Mountain View, California, organisation as a "major update" developed by an "an international community of contributors".
The browsers could be downloaded at the website www. getfirefox.com.
In the two years since its release by the nonprofit Mozilla Foundation, the Firefox browser has won millions of devotees worldwide.
"Firefox 2 delivers the best possible online experience for people today," said Mozilla chief executive Mitchell Baker.
Localised versions of the browser were available in 35 languages and tailored to work with Windows, Macintosh or Linux computer operating systems, according to Mozilla.
Firefox has 11 per cent of the web browser market, compared to the 86 per cent commanded by Internet Explorer and one per cent for Opera software, according to recent figures from Onestat web analytics firm.
Firefox simplified working in browsers, the boxes that show website pages on computer screens.
A strong advantage of Firefox has been a design that enables users to keep a set of browser windows open simultaneously and click easily between them with index tabs.
Firefox 1.0 has gained popularity
with companies and young users
Microsoft built that coveted feature into its new Internet Explorer Seven software.
Both internet navigation systems allow updated online feeds of news headlines or other information by means of Really Simple Syndication (RSS) and boast improved security against online hackers and scammers.
They were also designed with functions to check word spellings.
Particular safeguards were installed to thwart "phishing", tricking people into entering personal data such as credit card numbers on bogus websites designed to appear legitimate.
Mozilla was originally a web navigator code name at defunct internet firm Netscape when it dominated the internet browser world more than a decade ago.
Netscape fell from glory, its browser eclipsed by Internet Explorer, its company bought in 1998 by America Online and reduced to brand status.
The Mozilla Organisation was established in 1998 to complete the free, open-source software project and it registered as a nonprofit foundation in July of 2003.
The project was so lucrative that the foundation established a for-profit arm, Mozilla Corporation, two years later to handle distribution and sponsorship of the Firefox browser and a Thunderbird e-mail application.
Firefox 1.0 was launched in November of 2004 and gained popularity with companies and young computer users.
According to Jupiter Research, 44 per cent of US companies with more than 250 workers allow their employees to use Firefox on the job as compared to 26 per cent a year ago.
Some youth-oriented websites report that a third of their visitors use Firefox. Mozilla estimated that 350,000 people download its web navigator daily and that Firefox has 70 to 80 million users.