TeX formats, engines and distributions

Many LaTeX beginners struggle with a few basic notions, so let us explain them here together.

TeX formats

On the basic (“primitive”) commands of TeX, through clever use of macros, one can build elaborate languages and/or markup systems (called “formats”). Currently, three of them seem to be the most widespread:

• plain TeX (written by D. E. Knuth himself) – still very low-level, but having one big advantage: one can read and understand its codebase in a few days.
• LaTeX (originally by Leslie Lamport, now by the LaTeX team) – much more high-level, the most widespread TeX format. Many people, when saying TeX, really mean LaTeX.
• ConTeXt (by Hans Hagen) – even more high-level than LaTeX (and much more easily customizable), with different design goals and philosophy than LaTeX.

TeX engines

The program which actually interprets the TeX language (and the format used) is called the engine. Apart from the tex engine, written by DEK, there are quite a few modifications of it. Some of them are:

• pdftex, outputting pdf files instead of dvi (as in original TeX)
• etex, providing a few useful extensions to the TeX language
• pdfetex, which combines the above two (and is now the default LaTeX engine)
• xetex, which is Unicode-aware and can use all fonts available in the operating system (as opposed to original (pdf)?e?tex, which requires a special format of fonts); unfortunately no longer maintained
• luatex, which (apart from the mentioned features of xetex), has a scripting language Lua embedded (this is the default engine for modern versions of ConTeXt)

TeX distributions

A complete TeX system is a complicated thing. It has to contain the engine(s), the format(s), the fonts, the classes/packages (for LaTeX) and modules (for ConTeXt), and often contains additional programs and a TeX-aware editor. A distribution is such a system, together with an installer (and often a way to update it).

Currently, the most popular distributions are:

• MikTeX, available for MS Windows
• MacTeX, for Mac OS
• TeX live, for Unices and MS Windows (which is my personal recommendation)
• ConTeXt Standalone, a specialized, ConteXt-only distribution for Unices (including Mac OS) and Windows.