C language

Dennis Ritchie wrote the first C compiler.

In 1973, Version 4 Unix was famously rewritten in C. This was considered a "key pioneering approach" and an "unusual step that was visionary", as it went "contrary to the general notion at the time that an operating system's complexity and sophistication required it to be written in assembly language".

Rewriting Unix in C made it highly portable, enabling it to run on diverse platforms and "outlive its original hardware". This significantly reduced the amount of machine-dependent code needed for porting.

Dennis Ritchie attributed Unix's early success to the "readability, modifiability, and portability of its software that in turn follows from its expression in high-level languages" like C.

Unix system calls are regarded as C functions, and many Unix programs follow C's syntax

The C programming language soon spread beyond Unix and became ubiquitous in systems and applications programming

Both Unix and the C programming language were initially distributed to government and academic institutions, which led to both being ported to a wider variety of machine families than any other operating system.

A 2001 study of Red Hat Linux 7.1 revealed that 71% of its source code was written in the C programming language.

Even today, C remains highly relevant

• The Linux kernel is primarily written in C (along with assembly languages, Rust, and others).
• Linux distributions offer robust support for programming languages including C and C++.
• The GNU Compiler Collection (GCC) provides compilers for C, C++, and other languages.
• C++ (a descendant of C) continues to be one of the most widely used programming languages.