Google will drop support for Microsoft's Internet Explorer 7, and Mozilla's Firefox 3.5 browsers for its online apps, including Gmail and Docs.

"Beginning August 1, we'll support the current and prior major release of Chrome, Firefox, Internet Explorer and Safari on a rolling basis," said Venkat Panchapakesan, who heads Google's enterprise engineering team, in a company blog Wednesday. "Each time a new version is released, we'll begin supporting the update and stop supporting the third-oldest version."

By that scheme, Google will stop supporting IE7, Firefox 3.5, Apple 's Safari 3 and its own Chrome 9, all which have released two newer versions.

IE7, for example, has been superseded by IE8 and IE9; the same goes for Firefox 3.5, which has been replaced by Firefox 3.6 and Firefox 4.

After Aug. 1, users running those browsers may have trouble with some features in Gmail, Google Calendar, Google Talk, Google Docs and Google Sites. At some point, those apps may stop working entirely.

"For Web applications to spring even farther ahead of traditional software, our teams need to make use of new capabilities available in modern browsers," said Panchapakesan. "Older browsers just don't have the chops to provide you with the same high-quality experience."

Panchapakesan didn't mention Opera Software's Opera browser in his blog, an omission that prompted many users to leave comments.

"Lack of support for a browser as standards-compliant as Opera is absurd," complained someone identified as "Isildur."

Opera accounts for approximately 2% of all browsers, according to Web measurement company Net Applications, less than one-sixth the share of Chrome and less than one-third that of Safari.

The numerous "where's Opera"-style comments prompted one wag to say, " Wow, every existing Opera user left a comment here."

By Net Applications' statistics, the browsers Google will retire represent a minority of those in use.

Last month, IE7 accounted for 7% of all the browsers used worldwide, said Net Applications on Tuesday. Firefox 3.5 owned an even-smaller share of 1.4%, while Safari 3 accounted for only 0.1%. Altogether, the browsers destined for the dustbin controlled less than 9% of the browser market.

This was not the first time that Google has warned customers and users to upgrade to a newer browser. In January 2010, the search giant said it was dumping Google Docs support for IE6, the Microsoft browser that still accounts for 10.4% of all browsers in use.

Many IE6 users, however, are in China, where the government blocks access to Google's online applications, and with which Google has a contentious relationship .

But while Google and others have stopped supporting the 10-year-old IE6, Google is one of the first online software vendors to drop 2006's IE7 from a support list. Microsoft, for instance, has committed to supporting IE7 on Windows XP until April 2014, and on Vista for three years longer.

Panchapakesan urged people running one of the browsers on Google's kill list to upgrade to a newer edition.

The end-of-support plan for Google Apps will not disrupt access to its search site using older browsers.

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@computerworld.com .

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This story, "Google Drops Support for IE7, Other Aging Browsers" was originally published by Computerworld .