GNU/Linux is a free and open source operating system, a collaborative effort between the GNU project (formed 1983) and the Linux kernel development team. It's used in embedded systems, mobile phones (Android, Chrome OS), and GNU can be used without Linux (Debian/kFreeBSD, Guix GNU/Hurd).

The community covers distributions including Arch, elementary OS, Gentoo, openSUSE, Debian-based (Linux Mint, MX Linux, Pop!_OS, Ubuntu variants), Red Hat family (Alma, CentOS, Fedora, Rocky Linux), Nix OS, Chrome OS, OpenWrt, and mobile (Android, Sailfish OS, PostmarketOS). Desktop environments: GNOME, KDE, XFCE, Cinnamon; window managers: i3, awesomewm.

Resources include kernel, admin, gaming, hardware, and distribution-specific subreddits. AMAs feature figures like Greg Kroah-Hartman, Matthew Miller, Tobias Zwick. Rules prohibit support requests, blog spam, memes, self-promotion over 10%, login-required links, NSFW, and fluff images.