Text-rendering

The CSS   property is used on Windows and Linux to provide information to the rendering engine about what sorts of tradeoffs to make when rendering text, in order to optimize speed or legibility. Currently only Gecko 1.9 (Firefox 3.0) and WebKit 532.5 (Safari 5 and Chrome 4) support this property. This property does not function on Mac OS X. This is an SVG property, it is not defined in any CSS standard. Gecko and WebKit apply  also to HTML and XML content.

Values
One very visible effect is that  enables ligatures (ff, fi, fl etc.) in text smaller than 20px for some fonts (e.g. Microsoft's Calibri, Candara, Constantia and Corbel or the DejaVu font family).

CSS example: