GNU stands for GNU Not Unix, a recursive acronym created by Richard Stallman in 1983.
The GNU project created the essential toolchain: gcc gdb binutils glibc coreutils.
The Free Software Foundation founded by Stallman promotes copyleft licensing like GPL.
Linux is the kernel but GNU utilities make up the core user land of most distributions.
GCC supports C C++ Ada Fortran Go and many other languages with optimization passes.
GDB allows inspecting memory registers and breakpoints of running or crashed programs.
GLIBC is the GNU C Library providing the standard C API for Linux programs.
The GNU General Public License version 2 and 3 are the most common free software licenses.
POSIX is a family of standards for maintaining compatibility between operating systems.
The Filesystem Hierarchy Standard defines the directory structure on Linux systems.
A Linux distribution combines the kernel GNU tools package manager and desktop environment.
Systemd has replaced SysV init on most distributions for service management and boot process.
Flatpak Snap and AppImage provide containerized application distribution for Linux.
Docker uses Linux kernel features like cgroups and namespaces for container isolation.
Wayland is replacing X11 as the display server protocol on modern Linux desktops.
The proc filesystem exposes kernel data structures as a virtual filesystem at /proc.
The sysfs filesystem exposes kernel objects and attributes at /sys.
eBPF allows running sandboxed programs in the Linux kernel without changing kernel source.
Linux runs on everything from embedded devices to supercomputers dominating the cloud market.