Linux is the kernel that powers several different Operating Systems. GNU is a major component as it provides most of the core tools surrounding the kernel that allow it to work. And lastly, systemd is the first process that runs on most Linux distributions and manages services.
When people say, "Linux" they usually mean "Linux distributions," which are the above items bundled together with other software. You may have heard of some of the more popular ones: Debian/Ubuntu, Fedora/RedHat, Arch Linux, etc.
References for Newcomers
- kernel.org - the Linux kernel website
- gnu.org - the GNU website
- Arch Linux Wiki - made for Arch, but the best overall Linux reference
- systemd.io - the systemd website
- IRC channels on Libera - community support, most distributions have active channels
- DistroWatch - comprehensive list of Linux distibutions
So Many Choices, Where to Start?
The best part of Linux is diversity. The worst part of Linux is diversity. :-) Here are a few recommendations.
Easy, but opinionated:
- Ubuntu - if you know nothing, this is probably the easiest place to start
- Fedora - if you like semi-bleeding edge, but still well-tested
- Debian - if you prefer stability, Debian is hard to beat
Minimal, but some expertise required:
- Arch - bleeding edge software, systemd-based
- Void - bleeding edge software, runit-based
- Gentoo - for experts who want everthing compiled from source
Impractical, but educational:
- Linux from Scratch - for those looking to understand how it all works