Internet Explorer posted another major gain in share last month, the second in the first quarter of the year, perhaps signaling a turnaround in Microsoft's fortunes, a Web metrics company said Sunday.
Meanwhile, every rival, including Google's Chrome, which is usually the one stealing users, lost share.
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Internet Explorer (IE) gained 1 percent point during March, said measurement firm Net Applications, to end the month with a 53.8 percent share, its highest level since September 2011. Last month's growth was the second this year of 1 point or more.
Chrome lost a third of a percent point to close March with 18.6 percent, while Mozilla's Firefox slipped by about the same to 20.6 percent, the open-source browser's lowest number in more than three years.
Apple's Safari and Opera Software's desktop browsers also dipped, falling by two-tenths and one-tenth of a point, respectively, to 5.1 percent and 1.6 percent.
Chrome's decline is especially notable, as March's slide was the third consecutive month that Google's once-hard-charging browser lost share. In the first quarter of 2012, Chrome has dropped more than half a percent point, representing a 3 percent decline from the browser's December 2011 number.
Previously, Net Applications has attributed Chrome's skid to Google's January demotion of the browser's search ranking and then last month, to recalculations that eliminated the extra activity generated by Chrome's pre-rendering feature.
Google restored Chrome's search ranking last month.
It was unclear whether the rise of Internet Explorer (IE) and the fall of every rival was due to a rejiggering of Net Applications' numbers.
Like most Web measurement firms, Net Applications has more data on some nations -- the U.S., for instance -- and relatively small samples from others, such as China. To produce what it believes is a more accurate representation of global browser usage, Net Applications weights its Chinese data proportionally higher because that country has a greater percent of the world's Internet users than the U.S.
Net Applications uses online population numbers provided by the U.S. Central Intelligence Agency (CIA), which has regularly tracked big jumps in China's part of the browser-user pie, and corresponding drops in the percent of the world's users who hail from the U.S., Europe and other developed countries. Earlier this year, a company spokesman confirmed that it would revamp its calculations with newer CIA numbers at some point.
In February 2011, after Net Applications' last accounting change , IE's usage share jumped an eighth of a percent point, at that time its largest one-month increase ever.
Because Chinese users overwhelmingly rely on IE, or a modified version of Microsoft 's browser, the country can easily skew Net Applications' share estimates toward IE as more people there access the Web.