The GNU C Library, commonly known as glibc, is the GNU Project's implementation of the C standard library. Originally written by the Free Software Foundation (FSF) for the GNU operating system, the library's development had been overseen by a committee since 2001, with Ulrich Drepper as the lead contributor and maintainer. In March 2012, the steering committee voted to disband itself, in favor of a community-driven development process, with Ryan Arnold, Maxim Kuvyrkov, Joseph Myers, Carlos O'Donell, and Alexandre Oliva as non-decision making project stewards.

Released under the GNU Lesser General Public License, glibc is free software.

glibc was initially written mostly by Roland McGrath, working for the Free Software Foundation (FSF) in the 1980s.

In February 1988, FSF described glibc as having nearly completed the functionality required by ANSI C. By 1992, it had the ANSI C-1989 and POSIX.1-1990 functions implemented and work was under way on POSIX.2.

In the early 1990s, the developers of the Linux kernel forked glibc. Their fork, called "Linux libc", was maintained separately for years and released versions 2 through 5.

The C Standard Library is the standard library for the C programming language, as specified in the ANSI C standard. It was developed at the same time as the C POSIX library, which is basically a superset of it^{[citation needed]}. Since ANSI C was adopted by the International Organization for Standardization, the C standard library is also called the ISO C library.

Informally, the terms C standard library or C library or libc are also used to designate a particular implementation on a given system. In the Unix environment, such an implementation is usually shipped with the operating system and its presence is assumed by many applications. For instance, GNU/Linux comes with the GNU implementation glibc.

The C standard library provides macros, type definitions, and functions for tasks like string handling, mathematical computations, input/output processing, memory allocation and several other operating system services.

The application programming interface (API) of the C standard library is declared in a number of header files. Each header file contains one or more function declarations, data type definitions, and macros.

The GNU Compiler Collection (GCC) is a compiler system produced by the GNU Project supporting various programming languages. GCC is a key component of the GNU toolchain. As well as being the official compiler of the unfinished GNU operating system, GCC has been adopted as the standard compiler by most other modern Unix-like computer operating systems, including Linux, and the BSD family. A port to RISC OS has also been developed extensively in recent years. There is also an old (3.0) port of GCC to Plan9, running under its ANSI/POSIX Environment (APE). GCC is also available for the widely-used Microsoft Windows operating systems, and for the ARM processor used by many portable devices.

GCC has been ported to a wide variety of processor architectures, and is widely deployed as a tool in commercial, proprietary and closed source software development environments. GCC is also available for most embedded platforms, including Symbian (called gcce),AMCC and Freescale Power Architecture-based chips. The compiler can target a wide variety of platforms, including videogame consoles such as the PlayStation 2 and Dreamcast. Several companies make a business out of supplying and supporting GCC ports to various platforms, and chip manufacturers today consider a GCC port almost essential to the success of an architecture.^{[citation needed]}