Linux is a free, open-source, Unix-like operating system kernel created by Linus Torvalds in 1991. An operating system acts as the bridge between computer hardware and software applications.

Linux refers only to the kernel, while a complete operating system includes additional software such as the shell, libraries, package manager, and utilities.

What is Open Source?

• View source code
• Modify code
• Improve code
• Share improvements
• Redistribute software

Linux allows users to:

• Manage hardware resources
• Run applications
• Control memory
• Manage files
• Connect to networks
• Secure systems
• Execute multiple tasks simultaneously

What is an Operating System?
An Operating System (OS) is system software that manages all hardware and software resources.Without an operating system, a computer cannot function properly.

Examples include:

• Windows
• macOS
• Linux
• Android
• FreeBSD

History of Linux

Why was Linux Created?
Linus Torvalds wanted a free Unix-like operating system that anyone could modify and distribute.

The goals were:

• Free software
• Open development
• Better stability
• Better performance
• Community collaboration

Linux Architecture

Shell
The shell is the command interpreter that accepts user commands.
Popular shells:

• Bash
• Zsh
• Fish
• Ksh

Kernel
The kernel is the heart of Linux.
It manages:

• CPU
• Memory
• Processes
• Devices
• File Systems
• Networking

Hardware

Physical components:

• CPU
• RAM
• Hard Disk
• SSD
• Keyboard
• Mouse
• GPU
• Network Card

Popular Linux Distributions
A Linux Distribution (Linux Distro) is a complete operating system built around the Linux kernel. Since the Linux kernel alone cannot function as a full operating system, distributions combine it with essential software such as system utilities, package managers, desktop environments, libraries, and applications to create a ready-to-use platform.

Different Linux distributions are designed for different purposes. Some focus on ease of use, while others prioritize security, stability, performance, or customization.

Why Are There So Many Linux Distributions?

Linux is open source, allowing developers and organizations to create distributions tailored to specific needs.

Common goals include:

• Beginner-friendly desktop use
• Enterprise servers
• Cybersecurity and penetration testing
• Cloud computing
• Software development
• Scientific research
• Embedded systems
• Lightweight systems for older hardware

1. Beginner-Friendly Distributions

These distributions are easy to install and use.

Examples:

• Ubuntu
• Linux Mint
• Zorin OS
• Pop!_OS

2. Enterprise Distributions

Designed for business environments.

Examples:

• Red Hat Enterprise Linux (RHEL)
• Rocky Linux
• AlmaLinux
• SUSE Linux Enterprise

3. Security-Focused Distributions

Built for ethical hacking, penetration testing, and digital forensics.

Examples:

• Kali Linux
• Parrot Security OS
• BlackArch

Best for:

• Cybersecurity professionals
• Ethical hackers
• Penetration testers

4. Rolling Release Distributions

Receive continuous software updates instead of major version releases.

Examples:

• Arch Linux
• Manjaro
• openSUSE Tumbleweed

Best for:

• Advanced users
• Developers

Comparison of Popular Linux Distributions

How to Choose the Right Linux Distribution