Operating System
OS
- In Turkish
- İşletim Sistemi
- Pronunciation
- OP-uh-ray-ting SIS-tum
In short
An operating system (OS) is the core software that manages a computer's hardware, shares it out among programs and gives them a common way to use it.
What is an operating system?
Without an operating system, every program would have to drive the disk, screen, keyboard and network card itself. The OS does it once for everyone. Its kernel schedules processes on the CPU, gives each one its own protected memory, organizes files on storage, talks to devices through drivers and enforces who may access what.
Programs reach these services through system calls, such as opening a file, starting a process or sending data over the network, usually wrapped in the language's standard library. On top of the kernel, the OS ships user-space parts: a shell or desktop, system services, libraries and tools that make the computer usable.
The main families today are Windows; Unix-like systems, including Linux, which Linus Torvalds started in 1991 and which runs most servers and Android phones; and Apple's macOS and iOS, which descend from Unix. Unix itself was created at Bell Labs in 1969, and its ideas of processes, files and small composable tools still shape modern systems.
A common misconception is that the operating system is the desktop you see. The windows, icons and apps are the visible layer, but the essential part is the kernel underneath, which keeps programs from interfering with each other and shares the hardware fairly. Servers often run with no graphical interface at all.
Key takeaways
- An operating system manages hardware and runs programs.
- Its kernel handles processes, memory, files, devices and permissions.
- Programs use its services through system calls.
- Windows, Linux, macOS, Android and iOS are the main families.
- The desktop is only the visible layer; the kernel is the core.
Readers ask
What does an operating system do?
It starts and schedules programs, gives each one memory, stores and organizes files, controls devices through drivers, manages users and permissions, and provides the interfaces programs and people use.
What is the difference between an operating system and a kernel?
The kernel is the central part of the operating system that runs with full control of the hardware. The operating system also includes the user-space programs around it, such as the shell, system services and tools.
Is Linux an operating system?
Strictly, Linux is a kernel. Combined with tools, libraries and a package manager in a distribution such as Ubuntu or Fedora, it forms a complete operating system, which is what people usually mean by Linux.
See also
- KernelOperating Systems, p. 17A kernel is the core part of an operating system that manages the CPU, memory, and hardware devices and controls how programs get access to those resources.
- ProcessOperating Systems, p. 23A process is a running instance of a program, with its own memory space, resources, and at least one thread of execution managed by the operating system.
- System CallOperating Systems, p. 31A system call is a request from a program to the operating system kernel to perform a privileged action, such as reading a file or starting a process.
- File SystemOperating Systems, p. 12A file system is the part of an operating system that organizes data on a storage device into files and folders and tracks where each piece is stored.
- LinuxDevOps & Cloud, p. 33Linux is an open-source operating system kernel that powers most servers, cloud platforms, containers, and Android phones, usually packaged as a distribution.
- User SpaceOperating Systems, p. 36User space is the restricted area where ordinary programs run, kept separate from kernel space so a buggy or malicious app cannot take down the whole system.
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