8.1 Why do you need an operating system?

Software and the process of making software both benefit greatly from having an operating system. Without an operating system, each application would have to have its own user interface (UI) and all the code it needs to handle the low-level functions of the computer, like disk storage, network interfaces, and so on. Because there are so many different kinds of hardware, this would make every application much bigger and make it hard to make new software.

Software 101: A Complete Guide to the Different Types of Software - Coderus

Instead, many common tasks, like sending a network packet or showing text on an output device, like a screen, can be done by system software, which acts as a middleman between the apps and the hardware. The system software gives applications a consistent way to talk to the devices without the apps needing to know anything about the hardware.

As long as each application uses the same resources and services in the same way, that system software—the operating system—can handle almost any number of applications. This makes it much easier and takes much less time to develop and debug an application. It also makes sure that users can control, configure, and manage the system hardware through a common interface that everyone understands.