June's numbers hint that IE has joined Chrome in capturing users who last year would have gone to Firefox.
IE posted impressive gains in the U.S. in May, and that trend extended to other parts of the world during June. Microsoft's browser increased its usage share by 0.88 of a percentage point in Europe, and 0.81 of a percentage point in Asia last month, Vizzaccaro said.
IE did not sustain its large U.S. May leap last month, however: The browser's U.S. share climbed just one-half of one-tenth of a percentage point in June, compared to 0.76 of a percentage point in May.
Firefox again lost ground in the U.S. last month, as its usage share in this country dropped to 20%, a slip of 0.37 of percentage point, while Chrome's share rose 0.23 of a percentage point to 4.8%. Microsoft last month claimed that Chrome was "in retreat" in the U.S. market, but Net Applications' data shows that that wasn't the case in June.
Some versions of IE, however, continued to slide in share. IE7, which debuted in 2006 alongside Windows Vista, lost one-quarter of a percentage point to end at a historical low of 11.8%. The even older IE6 -- which Microsoft is determined to kill -- remained flat last month at 17.2%, and still accounts for more than 25% of the versions of IE still in use.
Mozilla, meanwhile, continued to convince Firefox users to upgrade to the newest edition, Firefox 3.6: More than two-thirds of all Firefox users are running that version. Chrome, which automatically updates in the background without user intervention, shifted dramatically to the newest edition, Chrome 5, last month. By the end of June, 85% of all people running Chrome had been updated to Version 5.
Google launched Chrome 5 in late May.
Rival Web metrics firm StatCounter's numbers for June were slightly different from those of Net Applications. The Irish company pegged IE's global usage share at 52.9%, an increase of just 0.09 of a percentage point over May, and it had Firefox at 31.2% and Chrome at 9.2%, for a decline of one-half of a percentage point and an increase of six-tenths of a percentage point, respectively.
Vizzaccaro wasn't about to declare that IE's June success would be a permanent trend in the browser battles. "I think we need to see a few more months of data," he said of IE's recent climb and Firefox's continued decline. "But if Microsoft continues to advertise IE, and then [follows that] with some serious advancement in IE9, it's possible."
Microsoft has released several developer previews of its next browser, IE9, but has yet to announce a final ship date, or even a release timetable for a public beta. The latter, however, is expected to launch in August, if a series of slides that leaked to the Internet are to be believed.
Aliso Viejo, Calif.-based Net Applications derives its data from browsing records of the 40,000 sites it monitors for clients of its consulting business. The firm's June browser usage share data is available on its site.
Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer, or subscribe to Gregg's RSS feed . His e-mail address is gkeizer@ix.netcom.com.