Table of Contents
Big Picture: Where Linux Fits
Linux is a family of operating systems built around the Linux kernel. It’s not just “one thing” you install—it’s a whole ecosystem:
- A kernel (the Linux kernel)
- A collection of user-space tools and libraries (often from the GNU project and others)
- A distribution that assembles everything into a usable system
You’ll later see “What is an operating system” and “The Linux kernel” in dedicated chapters. Here, focus on what makes Linux as a whole distinct:
- It’s widely used on servers, phones, embedded devices, and supercomputers.
- It follows open source principles: the source code is available, modifiable, and redistributable under certain licenses.
- It comes in many distributions (distros), such as Ubuntu, Debian, Fedora, and Arch, each packaging Linux differently.
When you say “I use Linux,” you really mean “I use a Linux-based operating system distribution.”
Core Ingredients of a Linux System
Even without going deep into the kernel or operating system theory, a typical Linux system includes a few standard building blocks:
- Linux kernel
The core that manages hardware, memory, processes, and device drivers. - C library and user-space utilities
Tools likels,cp,mv, andbashcome from projects such as GNU coreutils, util-linux, and others. - Init system / service manager
Oftensystemdon modern distros, which handles starting and managing background services. - Package manager
A tool for installing, updating, and removing software (e.g.,apt,dnf,pacman). The format and specific tool depend on the distribution. - User interfaces
- Command-line shells (e.g.,
bash,zsh) - Optional graphical desktops (GNOME, KDE Plasma, etc.)
A Linux distribution picks versions of all these components, configures them, and ships them as a coherent system.
What Makes Linux Different From Other OSes?
Linux-based systems behave differently from Windows and macOS in several ways that you’ll notice as a beginner:
1. Strong Unix Heritage
Linux was designed to be Unix-like:
- Everything is treated as a file (or behaves like one): hardware devices, processes, configuration, etc.
- The system encourages small, composable tools that you chain together.
- There is a strong emphasis on text-based configuration and the command line.
You don’t need to know historical Unix details yet, but remember: Linux borrows heavily from Unix ideas and conventions.
2. Open Source and Community-Driven
Linux is open source software, which means:
- The source code is publicly available.
- Anyone can inspect, modify, and share it, under license terms.
- Development is collaborative, involving companies, individual contributors, and organizations.
The practical effects for you:
- Linux is usually free to use and share.
- Bugs and features can be addressed by a huge global community, not just one company.
- You can often keep using Linux versions longer, even if a vendor stops supporting them, by switching to community-supported alternatives.
3. Many Flavors (Distributions)
There is no single “official” Linux for end users. Instead, there are many distributions:
- They all share the same kernel family, but:
- Different package managers (
apt,dnf,pacman, etc.) - Different defaults (desktop environment, tools, configuration)
- Different release policies (frequent rolling updates vs. periodic stable releases)
Later chapters cover distributions in depth. For now, understand that:
- “Linux” is the underlying engine.
- The distro is the full car: engine, body, controls, and extras.
4. Separation of Kernel and User Space
Linux strongly separates:
- Kernel space: core system code (the Linux kernel) with full access to hardware.
- User space: everything you run as a user (apps, shells, graphical environment) with limited, controlled access.
This separation improves:
- Stability: A misbehaving app is less likely to crash the whole system.
- Security: Ordinary programs don’t directly poke hardware; they ask the kernel via system calls.
Where You’ll Encounter Linux in Real Life
Linux powers an enormous variety of systems. You may already be using it without realizing it.
1. Servers and Cloud
Linux dominates servers:
- Web servers hosting websites and APIs
- Database servers (MySQL, PostgreSQL, etc.)
- Cloud platforms like AWS, Azure, and Google Cloud almost always run Linux under the hood
If you interact with websites, online services, or cloud tools, Linux is almost certainly involved.
2. Desktops and Laptops
You can install Linux as your everyday operating system:
- Common desktop distributions:
- Ubuntu
- Linux Mint
- Fedora Workstation
- openSUSE
- Key differences compared to other desktop OSes:
- Multiple desktop environments (GNOME, KDE, XFCE, and more)
- Flexible customization and theming
- Extensive free software repositories
Linux desktops are popular among developers, system administrators, and privacy-conscious users.
3. Mobile and Embedded Devices
Linux is a natural fit for devices:
- Android phones run a Linux kernel (with Google’s user space on top).
- Smart TVs, routers, network switches, IoT gadgets, NAS devices often run Linux-based firmware.
- Embedded systems in industrial equipment, cars, and appliances are frequently Linux-based.
These systems may not look like a traditional “Linux desktop,” but they rely on the same kernel principles.
4. Supercomputers and High-Performance Computing
Linux is the standard OS for supercomputers:
- Almost all of the world’s top supercomputers run Linux.
- Linux’s flexibility, scripting capabilities, and networking stack make it ideal for massive parallel systems.
5. Development Environments
Many developers use Linux because:
- It provides the same tools and environment as servers.
- It supports powerful command-line tooling and automation.
- It integrates well with container tools like Docker and Podman.
Even on Windows, tools like WSL (Windows Subsystem for Linux) provide a Linux user space for development.
Why People Choose Linux
Different users are attracted to Linux for different reasons:
- Control and customization
You can choose your desktop environment, window manager, shell, and even swap out major components. - Cost
Most distributions are free to download and use without licensing fees. - Security and stability
Strong multi-user design, permission system, and widespread use of audited open source software. - Learning and career
Understanding Linux is valuable for careers in: - System administration
- DevOps
- Cloud computing
- Cybersecurity
- Software development
- Philosophical reasons
Some users prefer software that respects user freedoms and encourages collaboration.
How Linux Is Put Together: A Conceptual Stack
Ignoring low-level details (covered in other chapters), you can visualize a Linux-based system as layers:
- Hardware
CPU, memory, disks, network cards, GPU, etc. - Linux kernel
Talks directly to hardware via device drivers; exposes system calls to user space. - System libraries and core tools
C libraries (likeglibcormusl), essential commands (ls,cp,ps), shells (bash, etc.). - System services (daemons)
Web servers, database servers, logging services, network services, managed by an init system likesystemd. - User interface
- Text-based: terminals and shells
- Graphical: Xorg/Wayland, desktop environments, window managers
- Applications
Browsers, editors, games, office suites, development tools.
As a beginner, you’ll mostly interact with:
- Layer 5 (desktop and terminals)
- Layer 6 (applications)
- Occasional configuration of layers 3–4 (using commands and configuration files)
What “Linux” Means in Everyday Conversation
People use the word “Linux” loosely. It can mean:
- The kernel specifically (as in “the Linux 6.8 kernel adds new driver support”).
- The entire OS (as in “I installed Linux on my laptop”).
- A distribution (as in “I use Linux” when they mean “I use Ubuntu”).
Context usually makes the meaning clear:
- Technical discussions often distinguish “Linux” from “GNU/Linux,” “kernel,” “user space,” etc.
- For day-to-day use, “Linux” is fine shorthand for “a Linux-based operating system.”
What You’ll Learn Next
Other chapters in this part of the course will build on this overview:
- What is an operating system — The general OS concepts that Linux implements.
- History of Unix and Linux — How Linux originated and evolved.
- The Linux kernel — More detail on the kernel’s role and internal responsibilities.
- GNU and the Free Software Foundation — Where many core tools come from and why.
- Open source philosophy — The ideas and licenses behind Linux’s development.
- Where Linux is used today — Concrete case studies of Linux in desktops, servers, embedded, and more.
- Desktop vs server vs embedded Linux — How the same core technology is adapted to very different use cases.
For now, remember: Linux is a flexible, open, Unix-like operating system ecosystem that runs from tiny devices to the world’s largest computers—and you can use it on your own machine, too.