In Firefox 3.5 we included support for linking to TrueType and OpenType fonts. In Firefox 3.6 we’re including support for a new font format – the Web Open Font Format, or WOFF. This format has two main advantages over raw TrueType or OpenType fonts.
1. It is compressed, which means that you will typically see much smaller download sizes compared with raw TrueType or OpenType fonts.
2. It contains information that allows you to see where the font came from – without DRM or labeling for a specific domain – which means it has support from a large number of font creators and font foundries.