TeX
Donald Knuth once received the proofs for the second volume of The Art of Computer Programming. It was 1977, and the result disappointed him so much that he decided to stop everything. The typographic composition of his mathematical formulas appeared so mediocre that he chose to create his own system rather than continue writing his books. The printing industry was undergoing a technical upheaval: it was abandoning hot metal typesetting, where each character was cast in metal and assembled by hand, to adopt phototypesetting. This new method was cheaper and faster, certainly, but Knuth would not accept the decline in quality that came with it.
The Stanford computer scientist devoted his 1977-1978 sabbatical year to developing TeX. He did not simply write a page layout program: he designed a complete system with its document description language and its DVI output format, independent of the printer used. His first trials took place on a DEC PDP-10 computer, in the SAIL language. Frank Liang and Michael Plass, his students, tested successive prototypes and actively participated in the development.
TeX redefined the art of typesetting through its sophisticated algorithms. Frank Liang developed a hyphenation system that adapts to different languages, while Michael Plass helped Knuth design paragraph justification. The technical innovation lies in the concept of “boxes and glue”: TeX manages the spaces between elements like virtual springs that compress or stretch according to needs. This approach produces justification of unmatched quality.
Knuth accompanied TeX with a second system: METAFONT. Rather than drawing letter outlines as PostScript and TrueType would later do, METAFONT programs characters by simulating pen movements. This parametric method generates entire font families by modifying a few variables. The Computer Modern fonts, created with this tool, have visually marked all TeX documents for forty years.
In 1982, the rewrite in Pascal gave birth to TeX82. This language change improved portability and served as the foundation for all subsequent versions. Knuth then adopted an original version numbering system: the numbers tend toward π for TeX and toward e for METAFONT. This mathematical approach reflects his desire to definitively stabilize the system. He committed to correcting only serious bugs, guaranteeing that a document would always produce an identical result, even decades later.
The American Mathematical Society placed its trust in TeX for its publications. This adoption by a reference institution contributed to its dissemination in universities around the world. Leslie Lamport understood that Knuth’s system was too complex for many users. In 1984, he created LaTeX, a layer of simplified commands that hides technical complexity behind a logical interface. The author could now focus on the structure of their document rather than its formatting, and its success surpassed that of “plain” TeX.
Knuth also reinvented software documentation. He developed specifically for TeX the principles of literate programming, blending code and explanations in a single document. This approach produced exceptionally complete documentation that helps other programmers understand and modify the system. A user community formed around TeX. The TeX Users Group was founded in 1980 and published TUGboat, a technical journal that accompanied the system’s evolution.
TeX remains the reference tool for scientists. Mathematicians, physicists, and computer scientists use it extensively to write their papers. Extensions like pdfTeX, XeTeX, and LuaTeX have added new functions without altering the original typographic quality. Paradoxically, Knuth’s innovations have never been adopted by mainstream software. Microsoft Word or LibreOffice Writer offer significantly inferior typesetting despite the power of current computers.
The story of TeX shows how one man’s demand for quality can change an entire discipline. It demonstrates the importance of open source code and exemplary documentation for a software’s survival. In a world where technologies succeed one another at a frantic pace, TeX crosses decades while maintaining all its relevance. Knuth had planned to spend a few months on this personal project. Nearly half a century later, his work continues to typeset the most beautiful mathematical or literary texts on the planet.