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What is Linux?¶

Linux is a kernel.

A kernel is the core component of an OS. It decides which program gets CPU, memory, and disk attention.

Without a kernel, your hardware does nothing.

┌──────────────────┐              ┌──────────────────────────────────────────────┐
│ OPERATING SYSTEM │              │                  HARDWARE                    │
│ ┌──────────────┐ │              │  ┌─────┐  ┌──────┐  ┌────────┐  ┌─────────┐  │
│ │    KERNEL    │─│ ─ Manages ─> │  │ CPU │  │ DISK │  │ MEMORY │  │ DEVICES │  │
│ └──────────────┘ │              │  └─────┘  └──────┘  └────────┘  └─────────┘  │
└──────────────────┘              └──────────────────────────────────────────────┘

But a kernel alone is useless. That's where distributions come in.

What is a Distro?¶

Distribution (or distro) = kernel + everything else you need to actually use the computer.

The "everything else" includes:

• Graphical interface (what you click)
• File manager
• Drivers (eg. Wi-Fi, Bluetooth)
• Pre‑installed apps

All this together = the Operating System.

What is a Shell?¶

A shell is a program that interprets commands and knows how you speak to the kernel.

You type something. The shell translates it. The kernel executes it.

What is a Terminal?¶

A terminal is the UI window that runs the shell.

Flow: Using a Command¶

This is what happens when you type a command called ls into the terminal.

┌──────┐     ┌──────────┐     ┌────────────┐     ┌───────────┐     ┌──────────┐
│ YOU  │  →  │ TERMINAL │  →  │   SHELL    │  →  │   KERNEL  │  →  │ HARDWARE │
├──────┤     ├──────────┤     ├────────────┤     ├───────────┤     ├──────────┤
│ "ls" │     │ (Window) │     │(Language + │     │ (Manager) │     │  (Body)  │
└──────┘     └──────────┘     │interpreter)│     └───────────┘     └──────────┘
                              └────────────┘
  "ls"        keystrokes        finds "ls"        manages "ls"    disk reads bits
 +Enter                       asks permission

What is a Partition?¶

A partition is a slice of your hard drive that acts like a separate disk.

Common Linux partitions:

Check Your Understanding¶

Test yourself with these theoretical questions.

1. Is Ubuntu an operating system or a kernel?¶

2. What's the difference between a shell and a terminal?¶

3. Which partition holds your personal files?¶

4. What does the kernel actually do?¶