What Is an Operating System?

The computer is one of the most influential inventions of the 20th century. Today, nearly everything relies on computing power—from smartphones and cars to household appliances and smart lightbulbs. However, computer hardware alone is useless without a system that allows people and software to interact with it. That system is the operating system.

This article explains what an operating system is, why it matters, what it does, and the main types of operating systems in use today.

Why Is an Operating System Important?

An operating system (OS) acts as the intermediary between computer hardware and software applications. Without an OS, software developers would need deep knowledge of each hardware component their program runs on and would likely have to write separate versions of the same application for different devices.

Every application would also need to manage tasks such as creating windows, handling storage, communicating over networks, and interacting directly with hardware using low-level machine code. Even small hardware changes—such as replacing a disk drive or Wi-Fi adapter—could require rewriting applications.

Operating systems solve these problems by abstracting hardware complexity and providing consistent services to applications, making software development practical and scalable.

What Does an Operating System Do?

Modern operating systems are complex and handle many critical tasks, including:

Processor Management

The OS determines which processes use the CPU and for how long. This process scheduling ensures that multiple applications can run smoothly at the same time by allocating and reclaiming CPU resources as needed.

Memory Management

The OS tracks how much memory (RAM) is available, assigns memory to running processes, and frees it once processes finish. This prevents applications from interfering with one another and helps optimize system performance.

Device Management

Operating systems include hardware drivers that allow software to communicate with devices such as keyboards, printers, storage drives, and network adapters. The OS controls access to these devices and manages input and output between hardware and applications.

File Management

The OS maintains a file system that organizes data into files and directories. It tracks file locations, metadata (such as creation and modification dates), and access permissions, mapping virtual file structures to physical storage.

Security

Operating systems manage user accounts and permissions, ensuring that users can only access files and applications they are authorized to use. Many OSs also support file encryption and other security mechanisms.

Core Parts of an Operating System

Operating systems consist of two primary components: the kernel and the shell.

Kernel

The kernel is the core of the operating system. It loads when the computer starts and remains in memory at all times. The kernel directly controls hardware and manages communication between hardware and software. Its responsibilities include memory management, process scheduling, device control, input/output operations, and handling system calls.

Shell

The shell is the interface between the user and the kernel. It allows users and applications to interact with the operating system. Users can access the shell through graphical interfaces or command-line tools, while applications rely on it to request services from the kernel.

Types of Operating Systems

Although operating systems share common functions, different types are designed for specific hardware and use cases.

General-Purpose Operating Systems

These are the most common operating systems, used on desktops and laptops. They are designed to support a wide range of applications and hardware configurations.

Examples include:

• Microsoft Windows – First released in 1985, Windows is one of the most widely used operating systems for personal and business computing.

• Apple macOS – Designed specifically for Apple computers and tightly integrated with Apple hardware.

• Unix – Developed in the 1970s, Unix was one of the earliest multi-user operating systems.

• Linux – A free, open-source OS based on Unix, widely used for servers and web services due to its efficiency and flexibility.

Mobile Operating Systems

Mobile operating systems are optimized for smartphones and tablets. The two dominant platforms are Android, used by many manufacturers, and iOS, developed exclusively for the iPhone.

Network Operating Systems

Network operating systems support communication and resource sharing across local area networks (LANs). They are commonly used in routers, switches, firewalls, and other networking equipment to manage protocols and data traffic.

Embedded Operating Systems

Embedded operating systems run on specialized devices such as ATMs, point-of-sale systems, and Internet of Things (IoT) devices. These systems are lightweight, highly reliable, and designed to perform a limited set of tasks consistently.

Real-Time Operating Systems

Real-time operating systems (RTOS) are used in environments where timing is critical. They process input from sensors and respond within strict time limits, making them essential for industrial automation, robotics, and control systems.

Conclusion

Operating systems are fundamental to modern computing. Developers interact with them constantly, and learning to program effectively means understanding how to work with an OS rather than against it.

Whether you are building mobile apps, desktop software, or embedded systems, mastering how operating systems manage resources, processes, and hardware is a key step toward writing efficient and reliable code.