How it works
At the centre is the kernel, which schedules programs on the processor, hands out memory, talks to hardware through drivers and enforces permissions. Around it sit the file system, networking, the graphical shell (desktop, taskbar, home screen) and the system libraries that apps call, known as APIs. Apps never touch hardware directly; they ask the operating system.
Desktops run Windows, macOS, Linux or ChromeOS; phones run Android or iOS; most servers and cloud machines run Linux. An app built for one system does not run on another without being rebuilt or ported, which is why cross-platform frameworks exist, and why installers, signing and app stores differ on every platform.
Related terms
More in Desktop apps
Operating systems