Fontspec is a package for XeLaTeX and LuaLaTeX. It provides an automatic and unified interface to feature-rich AAT and OpenType fonts through the NFSS in LaTeX running on XeTeX or LuaTeX engines.
The package requires the l3kernel and xparse packages from the LaTeX 3 development team.
The current release of this package typesets mathematics with unicode input and using OpenType maths fonts. (There is little compatibility with older maths packages.) XeTeX support is well tested, though LuaTeX support less so.
The package can typeset using STIX fonts, the XITS development of those fonts, the Asana-Math fonts and the commercial Cambria Math fonts. There is no support yet for any extra alphabets in the Unicode ‘private use area'.
The package relies on recent versions of the fontspec package and the l3kernel and l3packages bundles.