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:

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:

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: