Dennis MacAlistair Ritchie (September 9, 1941 – October 12, 2011) was an American computer scientist who "helped shape the digital era." He created the C programming language and, with long-time colleague Ken Thompson, the Unix operating system. Ritchie and Thompson received the Turing Award from the ACM in 1983, the Hamming Medal from the IEEE in 1990 and the National Medal of Technology from President Clinton in 1999. Ritchie was the head of Lucent Technologies System Software Research Department when he retired in 2007. He was the 'R' in K&R C and commonly known by his username dmr. Ritchie was born in Bronxville, New York. His father was Alistair E. Ritchie, a longtime Bell Labs scientist and co-author of The Design of Switching Circuitson switching circuit theory. He moved with his family to Summit, New Jersey, as a child, where he graduated from Summit High School. Ritchie graduated from Harvard University with degrees in physics and applied mathematics. In 1967, he began working at the Bell Labs Computing Sciences Research Center, and in 1968, he received a PhD from Harvard under the supervision of Patrick C. Fischer, his doctoral dissertation being "Program Structure and Computational Complexity".
Ritchie was best known as the creator of the C programming language, a key developer of the Unix operating system, and co-author of the book The C Programming Language, and was the 'R' in K&R (a common reference to the book's authors Kernighan and Ritchie). Ritchie worked together with Ken Thompson, the scientist credited with writing the original Unix; one of Ritchie's most important contributions to Unix was its porting to different machines and platforms.
The C language is widely used today in application, operating system, and embedded system development, and its influence is seen in most modern programming languages. Unix has also been influential, establishing concepts and principles that are now precepts of computing.