Firefox is on a decline. It may not be as steady as Internet Explorer's death spiral, and it certainly has not been going on for as long, but if the last three months are any indication, Firefox will never hit that 25 percent market share mark that looked all but certain just a few short months ago. Meanwhile, Chrome is still pushing steadily forward; in fact, it was the only browser to show positive growth last month.

Between January and February, Internet Explorer dropped a significant 0.60 percentage points and Firefox slipped 0.18 percentage points. Chrome jumped a sizeable 0.41 percentage points to 5.61 percent of the market while Safari fell 0.06. Opera, on the other hand, dipped from 2.38 percent to 2.35 percent, though we're still hoping version 10.5 will turn things around for the browser.

Data source: Net Applications

As you can see from the chart above, Firefox's decline is quite noticeable, and this is the first time in recent months that the browser has fallen three straight months in a row. Keeping that in mind though, the cumulative drop has not yet even reached a full percentage point, so Firefox can always reverse this trend. Mozilla failed to gain market share after the release of Firefox 3.6 two months ago; the new version has 5.16 percent of the market already, meaning it will easily pass all of Chrome this month. To fight back, Mozilla may have to start advertising its browser as much as Google does Chrome (on Google.com, YouTube.com, and so on) or even striking distribution deals with OEMs like Google did with Sony in September 2009.

Data source: Net Applications

In contrast to Firefox, Internet Explorer's decline is a much more noticeable trend. Nevertheless, IE is still used by more than half of all users and since the start of 2010, IE8 was being used by one in four users on the Web. The importance of having a default browser on the dominant operating system is still the biggest factor in browser adoption. IE7's decline is actually much faster than IE6's, which is unfortunate, and can be attributed to businesses still using customized intranet applications as well as the fact that XP's share is much bigger than Vista's. We think the debut of IE9 should shake things up a bit.

With Microsoft beginning to roll out the browser ballot in the EU, the months ahead are likely to see some more significant market share fluctuations. Some users who know nothing but IE will be confronted with other browsers for the first time, and it's all but certain many of those will give one of the other options a spin, if only out of curiosity. Don't be surprised if IE sees a sharper market share drop in the months ahead.

You can see the market share pie for February 2010, according to Net Applications, at the top of this post. The graph just above shows how things at Ars are very different: Firefox continues to dominate, but the default browsers for Windows and Mac OS X still show their strength, and Chrome's lead over Opera is much more significant at Ars. Compared to last month, Firefox gained share, while Safari and IE both dropped. Meanwhile, Chrome gained, as did Opera. Once again, Chrome's gain was the biggest change.