This is a must have if you are a serious TeX/LaTeX user. Knuth, the creator of TeX, discusses the concepts (eg. boxes and glue) and algorithms (line breaking, page breaking, spacing in equations) underlying the program and discusses tips, tricks and pitfalls.Even if you have no wish to poke into TeX's internals, the TeXbook is worth reading as a masterpiece of technical writing. Knuth asks you to solve exercises and tackle difficult passages marked with "dangerous bend" signs. He rewards you with witty epigraphs and in-jokes. (Regarding the pronunciation of TeX: "When you say it correctly to your computer, the terminal may become slightly moist"). Realizing how much thought Knuth has put into the design of TeX will make it harder for you to cut corners the next time you start a creative project. Among programming books I have read, onlyK&R;has helped me more in improving myself intellectually.