XeTeX is an extension of TeX that integrates TeX's typesetting capabilities
with (a) the Unicode text encoding standard (supporting most of the world’s
scripts) and (b) modern font technologies (TrueType and OpenType) and text
layout services (AAT, OpenType layout, SIL Graphite) provided by the host
operating system and available libraries.
With XeTeX, the advanced typographic features provided by OpenType fonts become
available for all TeX users, as well as support for complex non-roman scripts.
XeTeX also eliminates the complex task of managing a TeX font installation.
XeTeX is now part of the standard TeX distribution TeXLive and works well with
TeX macro packages like LaTeX and ConTeXt.