The growth of the Firefox web browser is one that’s been spurred on by word-of-mouth referrals, volunteerism and community-funded advertising campaigns to raise awareness. Over the years, the alternative web browser slowly chipped away at dominant Internet Explorer’s market share, despite its competitor’s advantage of coming bundled with the Windows operating system. By January of last year, Firefox topped 20% market share and by December, it reached 22%. But now, that growth has stalled. Actually, it has declined a slight 0.18 percentage points over the past month. Meanwhile, IE declined by 0.60 points.

And what’s to blame for these drops? None other than Google Chrome, the speedy WebKit-based browser from the Internet search giant which will soon be the basis of a new netbook operating system by the same name.

Chrome Gains While Others Drop

Between January and February, Google Chrome was the only browser to gain market share, reports Ars Technica, who gathered their data from Net Applications. By month-end, Chrome reached a 5.61% market share, a decent slice of the pie and more than other browsers like Apple’s Safari (4.45%) and Opera (2.35%), both of which have been around far longer.

You could argue that Chrome’s growth has to do primarily with who makes it: Google, of course. Thanks to advertisements for the new browser right on the homepage, Google has a platform for getting word out to an audience of millions quickly. However, those ads have been gone for some time now and Chrome still climbs. Why is that?

Interestingly enough, it’s not due to an advanced feature set. Chrome has been notorious for lacking even the most basic browser features, having initially launched without support for RSS feeds, extensions or a Mac version (all of which have been added now, RSS support via an optional extension, though). Yet despite these missing features, Chrome managed to capture 1% of the browser market within the first day of its release back in September 2008.

Chrome is Fast, but Not the Fastest

One factor that may make the browser so appealing is its speed. Based on the open source Webkit engine, which also powers Apple’s Safari browser, Chrome easily beats out Firefox and IE in a number of browser speed tests. However, speed can’t be only reason for its climb – independent browser Opera beat Chrome in several categories including browser boot-up and Javascript performance, for example. And with the latest Opera release, the company claims they’ve created “the world’s fastest browser for Windows.” And our own Frederic Lardinois confirmed this by doing speed tests.

Chrome’s Rise Due to Extensions and Mac Version?

So if it’s not speed alone, what else may be driving Chrome’s growth? Besides the release of a long-awaited Mac version in December, another factor could be the launch of extensions for Chrome. These add-on software applications put the Google browser more firmly on the same playing field as the others in the market. Many heavy web surfers rely on particular extensions, having grown comfortable with their favorites over the years. Some would even say they require them in order to work effectively on the web.

Or Is It Bookmark Sync?

In addition, Chrome recently released a handy “bookmark sync” feature last month. This lets Chrome users keep their favorite saved websites synced in between multiple computers just by associating a Chrome installation with their Google account.

Still, no single Chrome feature can account entirely for its rapid growth. Opera is faster, Safari is speedy as well, all offer extensions and Safari supports Mac and PC, too. So perhaps what’s really appealing about Chrome is its simplicity. With a design that eschews search boxes and heavy toolbars in favor of one big combo search/address box, only four navigation/action buttons and just two menu buttons which are labeled with icons, not names, Chrome keeps the focus on the web, not the browser. And that may be its best selling point of all.