C

In the early 1970s, Bell Labs remained a centre of intense technological innovation. Dennis Ritchie, an American engineer trained at MIT with a doctorate in physics, had been working since 1967 in the Murray Hill laboratories in New Jersey as a systems computing researcher. In 1969 his colleague Ken Thompson designed the UNIX operating system, initially written in assembler on a DEC PDP-7 minicomputer, which limited its portability to other hardware architectures. Thompson and Ritchie had previously worked together on the B language, a simplification of Martin Richards' BCPL, but B remained too tightly bound to the PDP-7 to facilitate the rewriting of UNIX. Faced with this challenge, Ritchie undertook between 1972 and 1973 to design a new language, which he named C in reference to its predecessor B. His aim was to achieve a compiled language close enough to machine code to generate efficient code, while remaining abstract and portable. C combined the accessibility of high-level languages with the power and conciseness of assembly language. The language introduced novel concepts: explicit memory management through pointers, data structures, modular functions and a streamlined syntax founded on BCPL algebra. In 1973 Thompson and Ritchie rewrote nearly the entire UNIX kernel in C, demonstrating for the first time that a complete operating system could be written in a high-level language and remain compilable on various hardware architectures. Ritchie wrote the foundational document "The C Reference Manual" in 1974 to formalise the language, and collaborated with Brian Kernighan to publish in 1978 the reference manual "The C Programming Language," which became the canonical text in the field. Introduced to the computing community through Bell Labs technical memoranda from 1976, C spread rapidly through universities and industry. Its ANSI C standard was adopted in 1989, followed by the ISO C standard in 1990. C became one of the most influential and widely used languages in computing history. Decades after its invention, the majority of operating systems — UNIX, Linux, macOS, Windows in part, Android kernels — remain written in C or directly inherit its architectural concepts. The language remains the reference for embedded systems, kernels, databases and critical global infrastructure.