You turn on your computer and the desktop appears. That is the operating system at work. It manages hardware, runs applications, and provides a user interface. Without an OS, you would have to speak directly to the processor in binary. The OS is the translator and the manager.

The OS handles memory, storage, input, output, and security. It schedules which program runs when. It allocates memory so programs do not collide. It manages files and directories. It enforces permissions so one user cannot read another's data. It talks to drivers for printers, cameras, and network cards.

Major operating systems

• Windows: dominant on desktops
• macOS: Apple's desktop OS
• Linux: open source, servers and embedded
• Android: mobile, based on Linux
• iOS: Apple's mobile OS

Operating systems shape how we use computers. Windows favors compatibility. macOS favors integration. Linux favors freedom. Mobile OSes favor touch and battery life. The OS is the foundation. Everything else builds on it.