# Operating system

> The base software that runs a device and lets every app share its hardware.

- Level: Basic
- Topics: Software, Hardware
- URL: https://tidbit.legios.com.ar/operating-system/
- In Spanish: [Sistema operativo](https://tidbit.legios.com.ar/es/operating-system/)

An **operating system** (OS) is the software that starts when you turn on a device and stays in charge until you turn it off. Windows, macOS, Linux, Android and iOS are operating systems. Its job is to manage the hardware, the CPU, the memory (RAM), the storage, the screen, the network, and to share it fairly among all the apps you run.

Without an OS, every app would need to know how to talk to your exact disk, keyboard and Wi-Fi chip, and two apps could overwrite each other's memory. The OS hides those details behind a common set of services: "save this file", "draw this window", "send this over the network". It also keeps apps apart from each other, so a crashing app does not take the whole machine down, and asks your permission before one uses the camera or your location.

The core of an operating system is called the **kernel**: the part that talks directly to the hardware and decides which program runs on the CPU at each moment. Around it come the things you actually see, like the desktop, the file browser, settings and built-in apps. That is why an app made for one OS usually does not run on another without changes.

## An analogy

The manager of a busy shared kitchen. The cooks (apps) never fight over the stove directly: they ask the manager, who hands out burners, keeps each cook's ingredients separate and makes sure nobody burns the place down.

## Keep in mind

- Examples: Windows, macOS, Linux, Android, iOS.
- Shares the CPU, memory, storage and devices among all running apps.
- Its core, the kernel, talks directly to the hardware.
- Apps are written for a specific OS, which is why some only exist for one.

## Go deeper

- [Operating system on Wikipedia](https://en.wikipedia.org/wiki/Operating_system)
- [Kernel (operating system) on Wikipedia](https://en.wikipedia.org/wiki/Kernel_(operating_system))

## Related terms

- [Linux](https://tidbit.legios.com.ar/linux/): A free, open source operating system that runs most of the internet's servers.
- [CPU](https://tidbit.legios.com.ar/cpu/): The chip that runs your programs, one instruction after another, very fast.
- [RAM](https://tidbit.legios.com.ar/ram/): The computer's short-term memory: fast, small and wiped when you turn it off.
- [Wi-Fi](https://tidbit.legios.com.ar/wi-fi/): Networking over radio waves: the internet without the cable, within a few rooms.
- [Chip](https://tidbit.legios.com.ar/semiconductor-chip/): A sliver of silicon carrying billions of tiny switches that compute and remember.
- [Web browser](https://tidbit.legios.com.ar/web-browser/): The app that fetches web pages from the internet and draws them on your screen.