Firefox's gain comes at the expense of Internet Explorer, which dropped to 89.04% market share, from 90.31% in December. Net Applications reports that other browsers maintained their user base.
"Firefox is currently the only browser that is increasing market share on a monthly basis, and it is growing at the direct expense of Microsoft's Internet Explorer," Net Applications CEO Dan Shapero said in a statement.
Microsoft is taking steps to stanch defections. Last month in San Francisco at the RSA Conference, Bill Gates said Internet Explorer 7.0 will be released in beta form this summer. The company claims its updated browser will offer better protections against phishing, malicious software, and spyware.