Webpages containing a tag pointing to Chrome Frame switch automatically to "Google Chrome's speedy WebKit-based rendering engine" when the page detects that an IE user has Chrome Frame installed, according to Google. Chrome Frame runs on IE versions 6, 7, 8, and 9.
But today, Google said the plugin isn't needed anymore and it will stop receiving support and updates entirely in January 2014. "It’s unusual to build something and hope it eventually makes itself obsolete, but in this case we see the retirement of Chrome Frame as evidence of just how far the Web has come," Chrome engineer Robert Shield wrote in the Chromium blog.
The browser market is much different today than it was in 2009. Internet Explorer has become much better and Microsoft has embraced HTML5. Usage of severely-out-of-date versions of IE has dropped. Chrome's popularity has soared, and Google recently decided to create its own fork of WebKit.
Dumping Chrome Frame could cause a bit of grief for developers, as some commenters on Shield's blog post and on Hacker News point out. Google contends that there won't be too many annoyances and that there are fixes for those that will exist. On the whole, Google believes Web development today is a less frustrating experience than it was when Chrome Frame was devised.
"In 2009, many people were using browsers that lagged behind the leading edge," Shield noted. "In order to reach the broadest base of users, developers often had to either build multiple versions of their applications or not use the new capabilities at all. … Today, most people are using modern browsers that support the majority of the latest Web technologies. Better yet, the usage of legacy browsers is declining significantly and newer browsers stay up to date automatically, which means the leading edge has become mainstream."