The main software used to control the hardware of a computer is what we call an "Operating System." In the simplest of terms, it manages the hardware of the computer and also presents the UI for the programs and applications running inside the computer. It is the internal manager that keeps the whole system running together properly.

If we consider the example of an airport, then our

HARDWARE is the physical infrastructure, the planes and other stuff
SOFTWARE is the passengers and the different types of airlines
OPERATING SYSTEM is the air traffic control in this regard

Without an Operating System

Without an Operating System, each software would require access to the hardware, which means a major lack in security and always a silent threat lingering around.

Along with this fact, when one application has unrestricted access to your hardware, many other applications do not work with it, so then you will have to get rid of the previous application. To sum it up, it's hefty and annoying.

So using an operating system cuts down the amount of personal effort we have to put in in order for a basic task to be carried out.

Understanding System Privilege Layers

The basic system privilege layers are,

The Kernel Layer
The User Layer

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Kernel Layer

This is the layer at which the operating system talks directly with the hardware of our machine.

In simple terms, at the kernel level, the operating system has unrestricted access to our computer's RAM, CPU, GPU, etc. So we can imagine that this is a very foundational layer.

This is what allows us to make a container, as mentioned in my previous articles.

User Layer

This is the layer where all users and applications and all other tasks are done.

At this layer, no application or user has access to the hardware. This is, of course, intentional due to security reasons.

Now, to understand how tasks are done, basically whenever we save a file into the memory or require the use of RAM, the application requiring thus sends a request to the Kernel Layer.

Then the Kernel accesses the hardware and fulfills this request.

Again, on the user layer, nothing has access to the hardware of your machine.

Operating System's Security

Before any firewall, anti-virus or any anti-malware systems, our Operating System is the first to apply security features to our machine; it is the basic and foundational layer.

Starting with....

Authentication

Your passwords, pins, fingerprints, and face scans are managed in this authentication. It ensures that no individual other than you gains access to your computer.

Permissions

With permissions, it ensures what kind of data each user and application is allowed to access and read. It ensures that each application is in check and has no unrestricted access to anything on our computer.

Isolation

It isolates the kernel from the user layer. It ensures that each application is isolated from the kernel and has no way to gain unrestricted access to the hardware of the computer.

System Protection

It ensures that system files and settings are not subjected to unauthorized changes.

Interfaces of an Operating System

There are 2 basic interfaces for an operating system: the Command-Line Interface (CLI) and the Graphical User Interface (GUI).

Command Line Interface (CLI)

In this, you give text-based commands to the computer.

You are not shown any files or anything in a graphical way; rather, you are shown them in text format.

The command-line interface offers a fast, accuracy-based way of communicating with the computer.

But this also means that there is a specific syntax for the "text-based commands" you write.

So if your command's syntax is not right, your command is not right as well, and nothing will work.

But on the other hand, the execution of these commands is very fast and accurate, and the Command Line Interface is also used to execute advanced commands that you can not execute by the GUI.

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Graphical User Interface (GUI)

The GUI is what we users normally interact with the most.

It provides us with a graphical representation of all the information that we want to access on our computer.

From shortcut icons to folders, files, etc. Everything that is graphical and allows us to interact with it is a GUI.

Without that we would need to run a command just to access our files even then those files would still be text based but the GUI provides us with the graphical representation of the data that we store inside the computer, and it also provides us with the graphical representation of every other task which would be hard for us to carry out by giving out text commands in the "Command Line Interface".

Real World Operating Systems

Now that we have seen how an operating system works on a foundational level, allow me to introduce you to some very common real-world operating systems that are frequently used.

Desktop

Windows

The most common and widely used operating system on personal computers

Windows 10 (end-of-life)
Windows 11

macOS

Apple's desktop OS, known for its polished GUI and integration with other Apple devices

Sonoma (14)
Sequoia (15)
Tahoe (26)

Linux

Not a single OS but a family of open-source operating systems called distributions

Kali Linux
Linux Mint
Arch Linux

Server

Windows

Used in large networks, data centers, and corporate environments

Server 2016
Server 2019
Server 2022
Server 2025

Linux

The vast majority of web servers, trusted for its reliability and open-source nature

Ubuntu Server
Debian
CentOS
Red Hat

Unix

Large enterprises, finance, telecom, government

IBM AIX
Oracle Solaris

Mobile

Android

The most widely used mobile OS, which runs on phones, tablets, and smart devices

Android 14 - 16
Manufacturer versions

iOS

Apple's mobile OS running on iPhones, iPads, and other devices

iOS 17
iOS 18
iOS 26

Embedded and IoT Devices

Embedded Linux

Specialized OS built into devices with dedicated functions

OpenWrt
Ubuntu Core
Yocto Project

Real-Time OS

Designed for apps where tasks need guaranteed response times (aircraft controls)

FreeRTOS
VxWorks
QNX

Conclusion

To conclude the article, I must say that an operating system is like a steering wheel for a vehicle..We can operate a vehicle best by its steering wheel, and that is exactly the purpose our Operating Systems serve. They also provide us with a decent level of security, as I explained above. We can run servers, host websites, and do much more on the vast diversity of these Operating Systems. For example, Kali Linux is the Linux Distribution used by ethical hackers because of the 600+ tools it comes with. There's much more to say, but I believe this is it for this article. I hope to find you in another crisp article.