The Firefox browser caused a mild sensation through the early months of 2005 as it became clear that Mozilla Corp.'s open source software was drafting precious percentage points of market share from mighty Microsoft and its Internet Explorer.

Microsoft had been able to "cut the oxygen" from Netscape in an earlier browser war simply by offering Explorer for free, and insisting that it be pre-loaded on all PCs by defining it as an integral part of its Windows operating system. But then Mozilla matched Redmond's price point with Firefox, and touted its higher in-built security and relative invulnerability to viruses, spyware, and malware. Its usability was of a commercial grade, and although not every website supports it, Firefox was supported well enough by enough sites to merit its inclusion as a serious competitor to Explorer.

Firefox's market share started at a few percentage points, due to 8 million beta downloads, then grew at a rate of 0.5 percent per month. It finally leveled off at around 8.6 percent, according to analyst estimates, although Mozilla spokesperson Chris Beard, head of products and marketing, maintains that Firefox has around a 10 percent share.

"Mozilla is ecstatic about the success of Firefox over the past year," said Mitchell Baker (pictured), CEO of Mozilla Corporation. "We applaud the commitment of our global community of open source contributors to the shared goal of making the Web browsing experience better for everyone. We're excited to share the tremendous results of this ongoing collaboration when we release Firefox 1.5 later this year."

Now what? The 5 percent or so of the market (and the proportionally higher perecentage of developers using the Mac) may wonder what all the fuss is about, as they have Safari. Upstarts such as Norway-based Opera continue to make their own inroads, albeit often in emerging media such as handheld devices. Netscape Navigator, heir to the software that launched widespread access to the Web, was updated by current owner AOL in a troubled version earlier in the year and appears to be gaining no market traction.

Mozilla plans to reach beyond its current base of "power users," in its words, to greater percentages of the mainline consumer market. Anecdotal evidence suggests that, in an ironic phrase, viral marketing has led to much of the spread of Firefox over the past year. A group of, say, soccer parents is sitting along the sidelines, one of them complains about all the unwanted pop-ups, etc., someone suggests Firefox, and explains how easy it is to download and use. The younger generation of users under the age of 25 are Web-savvy in the way their parents were TV-savvy, and is also a base audience for Firefox.