What Is an Operating System?

Every computer needs a hidden manager that ensures everything works together smoothly. This manager is called the Operating System (OS). It decides which programs get to use the CPU, how memory is shared, how files are stored, and how applications connect to the internet.

When you click an icon or type into a terminal, you are touching the surface of the OS. Underneath, it is quietly juggling thousands of tasks to keep your system safe and stable.

1️⃣ What Is an Operating System?

An Operating System acts as both a referee and a translator between applications and hardware.

• Translator: Applications do not talk to hardware directly. They ask the OS to “save this file” or “connect to Wi-Fi.”
• Referee: The OS ensures that one program cannot crash or overwrite another.

A simple mental model:

Applications → Libraries → Kernel → Hardware

The kernel is the operating system core. It manages the CPU, memory, files, and devices. On top of it lives the user space, which includes programs, shells, and graphical interfaces.

Analogy: The OS is like the manager of a stadium. It turns on the lights, assigns lockers, coordinates referees, and ensures the scoreboard runs correctly. Without it, the game cannot happen.

2️⃣ What Jobs Does an Operating System Do?

• Runs programs (processes): Decides which application gets CPU time. For example, switching between a browser and a video call.
• Manages memory: Prevents applications from interfering with each other’s data.
• Handles files: Organizes everything into files and folders. Your “vacation photos” folder only looks neat because the OS keeps raw data in order.
• Talks to devices: Lets applications use printers, disks, and Wi-Fi cards through drivers.
• Controls networking: Manages your internet connection.
• Enforces security: Decides who can read, write, or execute files.

3️⃣ Windows versus Linux: Everyday Comparison

Feature	Windows	Linux
Interface	Standard desktop with Start Menu and Explorer	Many options: GNOME, KDE, or command line
Customization	Limited	Highly customizable at every layer
Software	Many commercial applications, strong gaming support	Large open-source ecosystem, package managers
Security	Antivirus and updates are common	Built-in permissions, fewer viruses, community review
Cost	Paid license (often bundled with hardware)	Free and open-source (most distributions)
Where used	Personal desktops, offices, gaming PCs	Desktops, servers, phones, routers, supercomputers

Takeaway: Windows dominates personal computers, while Linux quietly powers most of the rest of the world.

4️⃣ Different Types of Operating Systems

• Desktop OS: Windows, macOS, Ubuntu, Fedora
• Server OS: Windows Server, Linux distributions such as Debian or Red Hat Enterprise Linux
• Mobile OS: Android (built on the Linux kernel) and iOS (built on Darwin, a Unix-like system)
• Embedded OS: OpenWrt for routers, Yocto Linux for Internet of Things devices
• Real-Time OS (RTOS): Zephyr, QNX, FreeRTOS, used when strict timing is critical

5️⃣ A Quick Look at Boot

When you turn on a computer:

1. Firmware (BIOS or UEFI) wakes up the hardware
2. Bootloader (for example GRUB) loads the kernel
3. Kernel starts drivers and mounts the root filesystem
4. Init system (systemd or alternatives) launches services and your login screen

Analogy: This is like a relay race: the firmware hands the baton to the bootloader, which passes it to the kernel, which finally prepares user space.

How We Use Linux Every Day

Have you ever wondered what keeps your smart devices and digital world running so smoothly? Behind the scenes, a powerful operating system called Linux powers many of the technologies you interact with every day. Born in 1991 as a personal project by Linus Torvalds, Linux has grown into the backbone of modern computing. This chapter will show you how Linux quietly supports your daily life.

1️⃣ Linux in Everyday Devices

Linux is secure, flexible, and reliable. It is the foundation for many consumer technologies:

• Smart Televisions
  Many platforms such as Tizen and webOS are Linux-based, enabling smooth streaming and app usage.

• Android Smartphones
  Android is built on the Linux kernel, with specific adaptations for mobile devices.

• Tablets and E-Readers
  Many e-readers, including the Amazon Kindle, use Linux-based firmware for performance and battery life.

• Wi-Fi Routers
  A large number of home routers run embedded Linux under the hood (often OpenWrt with BusyBox) to keep networks fast and secure.

2️⃣ Linux on the Move: Cars, Planes, and More

Transportation systems also rely on Linux:

• In-Flight Entertainment (IFE)
  Many airline entertainment systems use Linux to manage movies, music, and seat-back applications.

• Cars and Autonomy
  Automakers widely use Linux for infotainment dashboards. Autonomous driving stacks are often developed on Linux, sometimes paired with real-time operating systems for safety-critical tasks.

Example: Automotive Grade Linux is a collaborative project supported by companies such as Toyota, Mazda, and Mercedes-Benz.

3️⃣ Linux in the Cloud and the Internet

Linux is the top choice for web services and cloud computing because it is stable and high-performing:

• Web Servers
  A large share of the web runs on Linux, with popular servers like Nginx and Apache.

• Cloud Computing
  Amazon Web Services, Google Cloud, and Microsoft Azure all run massive fleets of Linux and offer Linux as a first-class option for developers.

Interesting fact: Even Microsoft relies heavily on Linux within its Azure infrastructure.

4️⃣ Using Linux for Fixing and Recovering Systems

Linux often comes to the rescue when computers crash or files are lost:

• Recovery Disks
  Many emergency tools for Windows boot into small Linux systems to help diagnose problems.

• Backup and Rescue Tools
  Utilities such as Clonezilla and SystemRescue are Linux-based and help with backup and recovery.

5️⃣ Linux in Your Home Appliances

As homes become smarter, Linux powers more household gadgets:

• Smart Appliances
  Refrigerators, ovens, and washing machines with touchscreens often run Linux.

• Home Automation
  Devices controlling lights, cameras, or thermostats commonly use Linux for reliability and connectivity.

Example: Many smart speakers and home hubs run on stripped-down Linux systems optimized for connectivity.