What is Linux?
Linux is a powerful, open-source operating system that runs everything from smartphones and laptops to servers and supercomputers. If you’ve browsed the web, used an Android device, or interacted with any cloud service, you’ve been running on Linux.
Kernel vs. Operating System
Section titled “Kernel vs. Operating System”These two terms get conflated constantly - worth getting straight early.
- The Linux kernel is the core of the OS. It manages hardware resources (CPU, memory, I/O devices) and acts as the bridge between software and hardware. Created by Linus Torvalds in 1991, it’s open source under the GPL license.
- A Linux distribution (“distro”) is the kernel plus a curated set of system utilities, libraries, package management tools, and optionally a desktop environment. When people say “I run Linux,” they usually mean a distro like Ubuntu, Fedora, or Arch.
The distinction matters in practice: you can swap out the kernel version without changing your distro’s userspace, and you can run the same application across distros that share the same kernel ABI.
What Makes Up a Linux System
Section titled “What Makes Up a Linux System”| Component | What it does |
|---|---|
| Bootloader | Hands control from firmware (BIOS/UEFI) to the kernel. Common ones: GRUB, systemd-boot. |
| Kernel | Manages CPU scheduling, memory, devices, system calls. |
| Init system | First process after the kernel (PID 1). Brings up services and daemons. Modern standard: systemd. |
| Daemons | Background services (sshd, cron, NetworkManager, etc.). |
| Shell | Your command-line interpreter. Default on most distros: bash. Alternatives: zsh, fish. |
| Graphical server | Translates app drawing calls to display output. X11 (legacy) or Wayland (modern). |
| Desktop environment | The full GUI layer (GNOME, KDE Plasma, etc.). Optional - servers don’t need one. |
| Applications | Everything else you install and run. |
Where Linux Runs
Section titled “Where Linux Runs”Linux isn’t just servers. It’s the OS underneath almost everything:
- Web servers: ~70%+ of public web servers run Linux.
- Cloud infrastructure: AWS, GCP, and Azure all run Linux hypervisors. Most VMs and containers you deploy run Linux.
- Supercomputers: 100% of the TOP500 list runs Linux (as of 2023).
- Mobile: Android is built on the Linux kernel.
- Embedded systems: Routers, smart TVs, IoT devices, car infotainment systems.
Further Reading
Section titled “Further Reading” The Linux Kernel Archives Official home of the Linux kernel source and releases.
The Linux Kernel Documentation Comprehensive technical documentation maintained alongside the kernel source.