Safari 4 available as a public beta since February 24, the final version of Safari 4 was introduced on Monday at WWDC 2009.

Safari 4 is an incredible accomplishment on Mac and Windows with more than 11 million downloads in the first three days, Less than a week later said Philip Schiller, Apple’s senior vice president of Worldwide Product Marketing. “Safari users love the incredible speed and innovative features like Top Sites, Full History Search and Cover Flow.
Safari 4.0 gives outstanding speed to HTML and JavaScript and can be used on Leopard, Windows, etc. Safari 4 introduce Nitro JavaScript engine, which executes JavaScript at speeds 8 times faster than Internet Explorer. Safari 4 has superior crash resistance and is said to be 40 percent faster than its predecessors. Safari has a full history search and Spotlight text search of history. It also notifies users when updates are available.  extra features like full- page zoom, smart address field, tidy search field and Phishing and malware protection are built-in with Safari 4. The look is similar to windows to make people think comfortable using it.