WebKit is the open source web engine that is the bases for Safari, Dashboard, Mail, other applications. This open source project begin as part of KHTML, who provided Apple the original source code for Safari 1.0.
In an blog posting entitled Ten new things in WebKit 3, the WebKit Open-Source Project details the features in this latest Safari release:
01. Enhanced rich-text editing
02. Faster JavaScript and DOM
03. Faster page loading
04. Scalable Vector Graphics (SVG)
05. XPath
06. New and improved XML technologies
07. Styleable form controls
08. Advanced CSS Styling
09. Reduced memory use
10. Web developer tools