Donald Knuth, at Stanford University, published in 1968 the first volume of "The Art of Computer Programming", a work establishing the rigorous analysis of algorithm performance as a formal mathematical discipline within computer science. Knuth did not invent big-O notation — which comes from 19th-century number theory (Bachmann, Landau) — but he is the one who adopts, systematizes, and popularizes it as the standard tool for describing how an algorithm's running time or memory usage grows as a function of input size, independently of the specific hardware it runs on. This formalization allows algorithms to be compared objectively — determining, for example, that a sorting algorithm of complexity O(n log n) will always be more efficient than one of O(n²) beyond a certain input size, without needing to implement and test both. The volumes of "The Art of Computer Programming", published intermittently from 1968 to the present, become the canonical reference of theoretical computer science; Bill Gates once said that anyone who read the entire work and understood all its content should send him their résumé. Knuth also creates the TeX typesetting system (1978) out of frustration with the typographic quality available for his own books, and TeX becomes the de facto standard for scientific and mathematical publishing.