The C programming language was first developed in 1972. Dennis Ritchie created it at Bell Labs while improving the earlier B language for the PDP-11 computer and for Unix-related systems programming.
C grew from BCPL through Ken Thompson’s B. B was compact and useful, but it did not take full advantage of the PDP-11’s capabilities, including byte-addressable memory. Ritchie added richer data types, pointers and other features, and the evolving language was renamed C. The first release is conventionally dated to 1972, although development continued through 1973.
C became especially important because Unix was progressively rewritten in it. That demonstrated that a high-level systems language could produce efficient, portable operating-system code without requiring everything to be written in assembly language. The language later spread through the 1978 book The C Programming Language, written by Brian Kernighan and Ritchie, often called the K&R book.
C was standardized first by ANSI in 1989 and then internationally as ISO C. It remains influential in operating systems, compilers, embedded devices and programming languages descended from or inspired by it.