C is a general-purpose programming language created at Bell Labs as part of the early development of the Unix operating system. In his history “The Development of the C Language,” Dennis Ritchie writes that C “came into being in the years 1969-1973, in parallel with the early development of the Unix operating system,” with its most creative period occurring during 1972.
Ritchie describes C as derived from the typeless language BCPL, to which it added a type structure. The language grew up on the DEC PDP-11, a small machine, and was used as the implementation language for the nascent Unix system. This pairing of language and operating system is central to C’s story: Unix was largely rewritten in C, which made the system far easier to move to new hardware than if it had stayed in assembly language.
C gives the programmer close control over memory and machine resources while still offering higher-level constructs such as functions, structured control flow, and data types. That balance of low-level control and readable structure made it the standard choice for operating systems, compilers, and other systems software.
According to Ritchie’s account, the language was later officially standardized, and the widely used reference description was the book he wrote with Brian Kernighan. C went on to influence the syntax and design of many later languages and remains one of the most widely used programming languages in the world.