TeX is a system for computer typesetting. It is a powerful low-level markup and programming language that creates professional quality typeset text. The system was developed by Donald Knuth at Stanford University with the purpose of enabling anyone to generate high-quality books, and to develop a system that yields the same results whatever computer is used.
The books featured in this article are all available for free, and some of them are released under an open source license. Some of the books are designed for beginners, others help writers fully master the complexities of TeX.