XeTeX

XeTeX is a TeX-based typesetting engine created by Jonathan Kew that provides native Unicode input and direct access to OpenType and TrueType fonts. It is designed to work with TeX and LaTeX through the XeLaTeX format and typically outputs PDF directly. XeTeX reads UTF-8 source files and uses system-installed fonts, enabling documents that use diverse scripts without font conversion.

Key features include full Unicode support, OpenType font features (such as ligatures, stylistic sets, and old-style figures), and built-in support for complex scripts and bidirectional text via the ICU library. Font management is commonly performed with the fontspec package in LaTeX, which allows selection of installed fonts. XeTeX also supports multilingual typesetting with packages such as polyglossia and babel.

History and usage: XeTeX was first released in the 2000s and has since been integrated into major TeX distributions such as TeX Live and MiKTeX. It offers a convenient alternative to pdfTeX and LuaTeX for users who need direct OpenType font access and broad script support. In practice, documents are compiled with the xelatex command.

Limitations: some advanced microtypography features and certain packages behave differently under XeTeX compared with pdfTeX. Font licensing, platform differences, and memory usage can affect portability and performance. The XeTeX project remains maintained within the TeX ecosystem, with ongoing updates in TeX Live and related distributions.