Updated 30 October 2026.
An operating system coordinates the hardware and software on a computer. It shares processor time between tasks, manages memory, organizes files and helps apps use devices through drivers. Windows, macOS and Linux systems use these ideas, although their internal designs differ.
For example, a music app chooses which song to play. The operating system helps it read the file and send audio through the right device. The hardware does the physical work: the processor runs instructions, storage supplies data and the speakers produce sound.
Hardware, software and the operating system: what is the difference?
| Part | What it is | Example |
|---|---|---|
| Hardware | The physical parts of the computer | Processor, RAM, SSD, keyboard and sound device |
| Application software | Programs that do tasks for you | Browser, word processor or music player |
| Operating system | System software that manages shared resources and provides services to apps | Windows, macOS or a Linux distribution |
| Device driver | Software involved in communication between the OS and a device | A driver for a graphics card, audio device or printer |
The OS is software too. It works closely with hardware, but it is not a physical component like RAM or the CPU.
Simple diagram: how an app communicates with hardware
Requests a device operation
Manage the request and access to resources
Handle device-specific communication
Carries out the operation
This diagram describes a device operation. The CPU also runs application instructions directly in the appropriate execution mode. The OS does not translate every calculation an app performs.
What does the operating system manage?
Processor time: which task runs next
An app runs within one or more processes. Inside a process, threads are units of work that can be scheduled to run. The OS scheduler chooses which ready threads get processor time. Multiple processor cores can run work at the same time.
Microsoft‘s Windows scheduling guide explains how the scheduler uses priorities to choose the next thread. This is part of how your computer can keep a browser, music player and other apps active together.
Memory: giving programs space to work
RAM holds data and code that the computer is using. The OS tracks memory use and gives processes their own virtual address spaces: the memory addresses each process works with. Hardware and the OS translate these into locations in physical memory.
Microsoft’s virtual memory explanation describes this separation. Programs can also share memory through controlled mechanisms. Protection relies on access rules and processor features, rather than simply putting the entire OS into one untouchable block of RAM.
Some memory contents can move between RAM and storage through paging. As Microsoft’s physical-storage guide explains, virtual memory and the amount of installed RAM are different things.
Files and devices: handling requests consistently
An app can ask to open a file or send data to a device through OS services. In Windows, the I/O system routes device requests through the relevant software layers. I/O means input and output: data going into or out of a device.
The kernel is the central part of the OS that handles privileged tasks, including core resource management. Other OS components and services also take part, so the kernel is not the entire operating system.
A real example: opening a document from an SSD
- You choose a file in an app. The app asks the operating system to open it.
- The OS checks access and locates the data. The file system and storage software help handle the request. Data already in a cache may be available without another physical read.
- If device access is needed, drivers and the storage controller communicate with the SSD. The data becomes available in memory for the app to use.
- The processor runs the app’s code. The app interprets the document, and the display system helps show the result on screen.
These steps are an overview. The file format, storage setup and operating system affect the details.
Why are device drivers needed?
Apps should not need their own instructions for every printer, sound chip or storage controller. Drivers help handle the differences between devices. A driver is software that participates in device communication; it does not have to emulate the device.
Microsoft’s driver overview also explains that a request can pass through several drivers. Some come with Windows, while others are supplied for particular hardware. For a practical example, see our guide to finding the right Realtek audio driver.
What connects the user to the hardware?
You normally interact through an app, desktop interface or command line. These interfaces turn your choices into software requests. The operating system coordinates the shared resources and device access needed to carry them out.
That is why the OS is often called a bridge between users, applications and hardware. It is a useful description, as long as you remember that drivers, firmware and the hardware itself also do part of the work.
Does a slow PC always need a faster processor?
No. A slow task can involve processor load, limited available memory, storage activity, background apps or other problems. Microsoft’s PC performance guidance covers several possible causes.
In Windows, Task Manager can help you see which resources are busy. If a slowdown started after installing software, our guide to finding recently installed apps explains how to check the list and interpret the dates. A busy resource is a clue to investigate, rather than proof that you need to replace it.
Frequently asked questions
What is the main role of an operating system?
It manages shared computer resources and provides services that applications use. Its work includes scheduling processor time, managing memory, organizing files and coordinating device access.
Is the operating system hardware or software?
It is system software. The CPU, RAM and storage drive are hardware; the OS contains code that runs on that hardware.
Why do apps use the operating system to access hardware?
OS services provide a consistent way to request operations while managing permissions and shared resources. Drivers handle much of the communication needed for particular devices.
Which part of the OS interacts with hardware?
The kernel and device-related components are central to that work. Drivers and other layers take part too. In Windows, some device drivers run in user mode and many run in kernel mode.
Does the CPU run the application or the operating system?
It runs instructions from both. The processor switches between application code and OS code as work is scheduled and services are needed. Ordinary calculations do not all need to become OS requests.
Can an app directly change the OS’s memory?
An ordinary app normally cannot freely write to protected OS memory. Windows uses execution modes and memory protection to separate them. Microsoft’s user-mode and kernel-mode guide explains that distinction.
Is BIOS or UEFI the same as an operating system?
No. Firmware runs before the main OS starts. Microsoft’s Windows startup overview separates firmware, boot manager, OS loader and kernel stages.
Can a computer do anything before an OS is loaded?
Yes. Firmware can initialize hardware and run startup code. That is different from running your usual desktop apps, which are built for a compatible operating system and its services.