C is a general purpose programming language, although it has been heavily used as a systems programming language and is closely associated with the UNIX operating system on which it was developed at AT&T"s Bell Labs. This language is useful for writing compilers and operating systems, but it has also found its place with many different domains for programs both large and small. In particular the scientific programming and high performance computing communities have largely embraced the use of C in their code.

Many of the fundamental ideas of C were developed in the BCPL language, and then further evolved into the B programming language. Ken Thompson eventually created the C programming language for the first UNIX system on the DEC PDP-7 (shown below). Thompson introduced a variety of data types into C, which we will discuss later.