Introduction to Operating System
Last Updated :
22 Sep, 2025
An operating system acts as an intermediary between the user of a computer and computer hardware. In short its an interface between computer hardware and user.
- The purpose of an operating system is to provide an environment in which a user can execute programs conveniently and efficiently.
- The operating system (OS) is a program that runs at all times on a computer. All other programs, including application programs, run on top of the operating system.
- It does assignment of resources like memory, processors and input / output devices to different processes that need the resources. The assignment of resources has to be fair and secure.
Operating System and User Interaction
Every general-purpose computer consists of hardware, an operating system, system programs and application programs.
- The hardware includes CPU, ALU, memory, I/O devices, peripheral devices and storage devices.
- The system programs include compilers, loaders, editors and the OS itself.
- The application programs are user-level software that perform specific tasks.

An operating system is always running in the background to manage and coordinate the use of hardware resources among system and application programs for multiple users. The OS is not itself just a user interface. Instead, it provides an interface for user interaction, typically through:
- Command-Line Interface (CLI), via shells and terminal commands.
- Graphical User Interface (GUI), through windows, icons and menus.
Note: At the core of the OS lies the Kernel, which is the primary interface between hardware and software which handles low-level operations such as process management, memory management, file system control and device handling.
Goals of Operating System
Primary Goals
The primary goals of an operating system (OS) are to provide a easy to use and convenient environment for executing user programs.
- User Convenience : It should be easy to use, providing a user-friendly interface and making it simple to interact with the system.
- Program Execution: It facilitates the execution of user programs, providing the necessary environment and services for them to run.
- Resource Management: The OS manages and allocates the computer's resources, including the CPU, memory, disk storage and input/output devices, to ensure fair utilization.
- Security: The OS protects the system and user data from unauthorized access, ensuring the confidentiality, integrity and availability of information.
Secondary Goals
- Efficient Resource Utilization: It should aim to maximize the performance and utilization of computer resources like CPU, Memory and IO devices, ensuring that the system runs smoothly and efficiently.
- Reliability: It should be robust and reliable, able to handle errors and exceptions gracefully, ensuring that the system continues to operate smoothly. It should be modular in design and easy to debug.
Components of an Operating Systems
There are two basic components of an Operating System.
- Shell is the outermost layer of the Operating System and it handles the interaction with the user. It interprets input for the OS and handles the output from the OS.
- Kernel is the core component of operating system. The kernel is the primary interface between the Operating system and Hardware.
List of Common Operating Systems
There are multiple types of operating systems each having its own unique features:
- Windows OS : Developed by Microsoft. Used in personal computing, Business environment, Gaming.
- macOS : Developed by Apple. Used for creative industries (design, video editing, music production), Personal computing and Professional environments.
- Linux : Community-driven (various distributions). There are large selection of distributions (e.g., Ubuntu, Fedora, Debian). It is free to use and distribute. Used in servers and data centers, Development and programming, Personal computing for tech enthusiasts.
- Unix : Developed originally AT&T Bell Labs, various commercial and open-source versions available. Used in servers and workstations, Development environments, Research and academic settings
History of Operating System
The operating system has been evolving through the years. The following table shows the history of OS.
Era | Key Developments | Examples |
---|
1956 | The first Operating System was GM-NAA I/O in 1956 by General Motors. | GM-NAA I/O (1956) |
1960s | IBM developed a time sharing system TSS/360 | OS/360, DOS/360 and TSS/360 |
1970s | Unix popularized simplicity and multitasking; rise of personal computers with basic OSs. | Unix (1971), CP/M (1974) |
1980s | GUI-based OSs gained traction; networking features became standard. | Apple Macintosh (1984), Windows (1985) |
1990s | Open-source Linux emerged; GUIs in Windows and Mac OS improved. | Linux (1991), Windows 95 (1995) |
2000s-Present | Mobile OSs dominated; cloud and virtualization technologies advanced computing. | iOS (2007) android (2008) |
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