Apple has announced the public beta of Safari 4, describing it as the world's fastest and "most innovative" web browser for Mac and Windows PCs.

New features include top sites, for what's said to be a "stunning visual preview of frequently visited pages", full history search, and, borrowing from the iPhone and iTunes, Cover Flow, to "easily flip through web history or bookmarks" as well as "Tabs on Top", that claims to make tabbed browsing easier and more intuitive.

Other new features include a "Smart Address Field" with auto-complete, a "Smart Search Field" that uses Google Suggest or a list of recent searches, full page zoom, and, for the Windows version, a new "Windows-native look" that uses standard Windows font rendering and native title bar, borders and toolbars so Safari "fits the look and feel of other Windows XP and Windows Vista applications".

"Apple created Safari to bring innovation, speed and open standards back into web browsers, and today it takes another big step forward", said Philip Schiller, Apple's senior vice president of worldwide product marketing.

"Safari 4 is the fastest and most efficient browser for Mac and Windows, with great integration of HTML 5 and CSS 3 web standards that enables the next generation of interactive web applications".

Apple claims Safari 4 executes JavaScript 4.2 times faster than Safari 3, up to 30 times faster than IE 7 and more than three times faster than Firefox 3 and that Safari loads HTML web pages three times faster than IE 7 and almost three times faster than Firefox 3.

Safari 4 is a public beta for both Mac OS X and Windows and is available immediately as a free download at www.apple.com/uk/safari.