Donald Ervin Knuth is an American computer scientist, mathematician, and professor emeritus at Stanford University. Donald Ervin Knuth was born January 10, 1938, in Milwaukee, Wisconsin. After receiving his PhD, Knuth joined Caltech's faculty as an associate professor. He accepted a commission to write a book on computer programming language compilers. While working on this project, Knuth decided that he could not adequately treat the topic without first developing a fundamental theory of computer programming, which became The Art of Computer Programming. He originally planned to publish this as a single book. As Knuth developed his outline for the book, he concluded that he required six volumes, and then seven, to thoroughly cover the subject. He published the first volume in 1968. Just before publishing the first volume of The Art of Computer Programming, Knuth left Caltech to accept employment with the Institute for Defense Analyses' Communications Research Division, then situated on the Princeton University campus, which was performing mathematical research in cryptography to support the National Security Agency.