What is an operating system?

A user interacts with an operating system through a user interface (UI), which issues commands in a language the OS can understand. The UI can be either a graphical user interface (GUI) or a command-line interface (CLI). Billions of people rely on operating systems as the underlying management system for tasks like sending emails, browsing the internet, playing video games and more.

All computer systems—from mainframes to desktops to mobile devices—need at least one operating system to perform tasks, run applications and interact with the hardware.

In a report from Statista, Microsoft Windows is the most widely used operating system worldwide, controlling 67% of the desktop, tablet and console OS market.¹ Apple’s macOS ranks second in this category.

Android leads with a market share of approximately 72.04% in the mobile OS category, while Apple’s iOS holds the second spot with 27.49%.²

In the world of open source software, Linux is the most popular—widely favored by both organizations and individuals for its flexibility and security.

The history of the operating system (OS) began with early computers that required customized system software for task management. Initially simple and batch-oriented, operating systems evolved to support multitasking and interactive interfaces, driven by advances in hardware and software.

The invention of the integrated circuit (IC) in the 1950s led to microchips, which boosted processing power and reduced computer size, enabling more complex tasks. In 1964, IBM introduced the OS/360, which relied on assembly programming language, for their IBM System/360. The OS/360 standardized software across its mainframes, influencing future OS designs. In addition, the OS/360 was the first multiprogramming operating system, which could run numerous programs simultaneously on a single processor machine.

Over time, the OS/360 evolved into z/OS®, the modern OS for IBM mainframes. (Today’s IBM Z® mainframes also run on Linux and z/TPF, with multiple operating systems often running on a single mainframe.)

The development of the time-sharing OS Unix in the 1960s and 1970s set important precedents for modern operating systems by introducing concepts such as multitasking, portability and a hierarchical file system, which are foundational to today’s systems.

In the late 1980s and 1990s, graphics processing units (GPUs) were introduced to handle graphics processing. As GPUs evolved to support general-purpose computations, especially in the 2000s, companies including Apple and Microsoft began integrating them more deeply into their operating systems. Today, GPUs are a standard feature in most computing systems, powering everything from gaming and multimedia to scientific computing and machine learning (ML).

Innovations like virtualization and containerization emerged as the need for greater efficiency and scalability grew, especially in cloud computing. Virtualization allows multiple virtual machines (VMs) to run on a single physical machine. A hypervisor manages these virtual machines, acting like a lightweight operating system by handling resource management and memory allocation without the need of a full OS. VMware is considered the leader in the virtualization and hypervisor market.

Containerization builds on virtualization by offering a more lightweight approach to running isolated applications. Unlike VMs, containers do not include a full copy of the operating system. Instead, the container runtime engine (for example, Docker) is installed on the host system’s OS, acting as the interface through which all containers share the same OS. This capability allows containers to virtualize the OS, enabling applications and their dependencies to run independently on a single OS, improving resource efficiency.

In both single-user and enterprise contexts, an operating system (OS) manages and coordinates hardware and software, providing an environment where users can interact effectively. In enterprise settings, the OS supports larger-scale operations to support multiple users, processes and services across an organization, including the following:

• Process management: An operating system manages the execution of multiple processes and threads, including tasks like scheduling, synchronization and communication between processes. User applications interact with the OS through system calls to create, manage and terminate processes and facilitate interprocess communication. For example, in integration-centric business process management (BPM), the OS plays a key role in ensuring smooth interaction between various software systems. As IT teams or system operators integrate a CRM system with other enterprise applications, the OS manages APIs, allocates resources and secures data flow, enabling automated processes with minimal human intervention.

• Memory management: The OS allocates and controls computer memory. It ensures that programs have enough resources to run without interfering with others. It efficiently handles both primary memory (RAM) and auxiliary storage (hard disk drives, solid-state drives), by using paging and swapping to move data between them as needed.

• File system management: The OS organizes and retrieves files, managing directories, file naming and permissions. It ensures data integrity through mechanisms such as data validation, checksums and error-correcting codes.

• Device management: The OS manages input/output (I/O) devices (for example, keyboards, disk drives, printers, monitors), providing an interface for software to interact with hardware components. In a virtual environment, this includes VMs, virtual switches, and so forth.

• Security and access control: The OS enforces security protocols, including authentication, encryption and setting user permissions, ensuring only authorized access to computer resources.

• Networking: The OS manages networking, enabling communication between computers over LANs or the internet and handling protocols like TCP/IP.

• Error detection and handling: The OS monitors for software- and hardware-related errors, providing mechanisms for reporting and recovering from them.

• Resource allocation: The OS efficiently allocates resources like central processing unit (CPU) time, memory and I/O devices for optimal system performance.

• System performance monitoring: The OS tracks system performance (for example, memory usage, running processes, system logs) and adjusts processes or resources to improve efficiency.

An operating system consists of several core components working together to ensure system functionality and efficiency:

• Kernel

• Process scheduler

• Memory manager

• Input/output manager

• File system manager

• User interface

Operating systems can be categorized into several types based on their features, functionality and compatibility with different hardware and software applications. They include:

• Embedded operating systems

• Distributed operating systems

• Real-time operating systems

• Network operating systems

• Cluster operating systems

An embedded operating system is designed to manage hardware resources in specialized devices like smartphones, automotive systems and household appliances. Unlike general-purpose operating systems, embedded OSes are optimized for performance, efficiency and reliability in resource-constrained environments. They are typically lightweight, with minimal user interfaces, and they are built to run specific applications continuously or in real-time.

A distributed operating system coordinates multiple independent computers to work together as a unified system. It allows resources from different machines to be shared, providing a single, transparent interface to the user and application programs. The OS manages communication, data sharing and task synchronization across various nodes, ensuring that users can interact with the system without worrying about the physical distribution of the resources.

Google File System (GFS), for example, is part of Google’s distributed system architecture, allowing data to be distributed across many servers and ensuring high availability and fault tolerance.

A real-time operating system (RTOS) is designed to handle time-sensitive tasks with precise timing constraints. In an RTOS, the system guarantees that critical processes are completed within a specific time frame, ensuring predictability and stability.

These operating systems are used in applications like industrial automation, robotics and medical devices, which depend on control systems where delays or failures could have severe consequences. Real-time operating systems such as VxWorks are commonly used in embedded systems for aerospace and defense applications, where real-time responses are crucial for safety and performance.

A network operating system (NOS) is software that manages and coordinates the hardware and software resources of multiple computers connected in a network. It enables communication between devices, file sharing and resource management across the network.

A NOS typically includes features such as network security, user authentication and centralized administration, allowing system administrators to control access and configure settings across all connected devices. Examples of network operating systems include Microsoft Windows Server, Cisco IOS and macOS Server.

A cluster operating system manages a group of interconnected computers (nodes) that work together to perform tasks like a single system. These systems are typically used in high-performance computing (HPC) settings (for example, web hosting, scientific research) and provide load balancing, fault tolerance and resource sharing among the nodes. Cluster operating systems allow users to scale up computational power by combining multiple machines, improving overall system reliability and performance.

Hundreds of operating systems exist to serve a wide range of purposes, from personal computing and mobile devices to enterprise and cloud environments. These are some of the most prevalent:

• Linux

• macOS

• iOS

• Android

Linux® is an open source operating system widely used in desktops, servers and embedded systems. It is especially popular for server management, cloud infrastructure and software development.

Notable enterprise versions like Red Hat® Enterprise Linux (RHEL) and SUSE Linux Enterprise Server (SLES) are commonly used in business environments due to their stability and support.

Additionally, there are numerous Linux distributions tailored to various use cases, including Ubuntu, Fedora and Debian. These distributions make Linux highly versatile and suitable for personal computer use, development and specialized applications.

Microsoft Windows is one of the most widely used operating systems globally for personal and business use. Renowned for its user-friendly interface and versatility, it supports various software applications, from productivity tools like Microsoft Office to specialized programs for gaming, engineering and design.

MacOS (previously called OS X) is a Unix-like proprietary OS designed to run on Apple’s desktops, laptops and workstations (for example, iMac, MacBook, MacBook Pro). MacOS is especially popular among professionals in creative industries as it excels in areas like graphic design, video editing, music production and software development.

Apple iOS is a proprietary mobile operating system that runs on Apple mobile devices such as iPhones and iPads.

Developed by Google, Android is an open source mobile operating system widely used in personal and business smartphone devices.

The AI operating systems market is poised for significant growth, with research from Knowledge Sourcing Intelligence forecasting an increase from USD 12.496 billion in 2024 to USD 29.297 billion by 2029, at a CAGR of 18.58%.³

In enterprise environments, AI-powered operating systems leverage machine learning and automation to predict user behaviors, optimize resource allocation and adapt to changing workloads in real-time. Self-healing capabilities reduce downtime by automatically detecting and resolving issues, while AI-driven security systems identify and mitigate cyberthreats, ensuring enterprise data remains protected.

Leading operating systems like Windows and macOS incorporate AI to optimize resource management, enhance security (for example, Windows Defender Face ID) and provide personalized user experiences.