The February browser market share numbers are in, and it looks like it was a good month for Internet Explorer, but a bad one for Firefox. Internet Explorer is up 0.77 percent to 56.77, Firefox is down 0.99 percent at 21.74.

These gains were partly attributed to a change in Net Applications' calculations. The company uses demographic data from the Central Intelligence Agency to construct its estimates; the different measures it makes in different countries are scaled to take into account different population sizes and levels of Internet penetration. With the new CIA data, Western Europe—where Firefox has its highest usage rates—now represents a smaller share of the global Internet audience. This change should give Internet Explorer a one-off boost at Firefox's expense.

Chrome saw gains of 0.23 points, to 10.93, continuing that browser's steady growth (in the last year, it has doubled its market share). Safari saw negligible growth from 6.30 to 6.36 points. Opera saw a decline, down to 2.15 percent from 2.28. These browsers may have also been casualties of the decline of European influence on global browser statistics: prior to this February, Chrome has had a monthly growth rate of between 6 and 8 percent, but with these latest numbers it has dropped to growth of just 2%. Opera has also traditionally performed best in Europe.

Even with the change in demographics, past Internet Explorer trends continued; usage of Internet Explorer 8 has grown, from 34.17 to 34.95 percent, and usage of Internet Explorer 6 and 7 has declined, from 11.43 to 11.33 and 8.29 to 8.05 percentage points, respectively. Getting customers to upgrade to the latest and greatest version continues to be a far greater challenge for Microsoft than it is for the other browser developers. In contrast, overwhelming majorities of Firefox and Chrome users are using the latest versions of those browsers.

Beta browsers—Firefox 4, Internet Explorer 9, and Chrome 10—also put in a surprisingly strong showing. With 0.63, 0.59, and 0.31 percentage points respectively, it's clear that there are plenty of people out there who simply must have the latest and greatest Web browsing experience they can get.

Without knowing what the unadjusted numbers are, it's hard to tell whether this month's figures represent a halt in Internet Explorer's downward slide or a mere statistical anomaly. The imminent release of Internet Explorer 9—due some time between South by Southwest and Microsoft's MIX conference—and Firefox 4 may serve to reinvigorate both of those browsers. Google's advertising clout may, however, prevail.

As ever, our figures here at Ars buck the broader trends. February was a good month for Firefox and a stupendous one for Chrome (up 0.35 and 1.42 points respectively), and horrible for Internet Explorer and Safari (down 0.82 and 0.94 percent).