Mozilla's Firefox quietly gained enough users in March to grab 10 percent of the web browser market, according to a report from web audience measurement firm Net Applications.

Firefox was used by 10.05 percent of surfers last month, up from 9.75 percent in February. That compared to the 84.7 percent of users on various versions of Internet Explorer (IE) in March. In third place with 3.19 percent was Apple’s Safari browser, which used only on Macs.

In the past year, Firefox has gained 3.34 percent share while introducing version 1.5 of the browser with improved features. Internet Explorer has lost 3.89 percent, as users wait for IE7, which boasts improved features and security and is due out this autumn.

“With a strong feature set, aggressive product development cycle, open source platform and by offering the browser for free, Firefox has the strategy in place to maintain its growth,” Vincent Vizzaccaro, an analyst with Net Applications, wrote in yesterday’s report. But Microsoft “has the much easier task of defending an entrenched position rather than attacking one.”

Netscape was the fourth most popular web browser, with 1.05 percent of the market, followed by Opera with 0.54 percent and Mozilla with 0.34 percent.