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Beginner Topic 1 of 51 Operating Systems

What is an Operating System

Software managing hardware and providing services to programs.

How it works

An operating system is the software layer between applications and hardware. It manages the CPU, memory, storage and devices, shares them among many programs and provides abstractions such as processes, files and sockets. Core duties are process scheduling, memory management, file systems, device I/O, security and protection. It gives each program the illusion that it owns the machine.

Step-by-step walkthrough

  1. Applications such as a browser and a game run on top.
  2. They ask the OS for files, memory and network access.
  3. The OS shares the CPU, memory and devices fairly among them.
  4. It talks to hardware through drivers.
  5. It isolates programs, so one crash does not take down the machine.

Where it is used

Every laptop, phone, server, router and embedded device runs one, such as Linux, Windows, macOS, Android or an RTOS. Applications call it through system calls and standard libraries instead of touching hardware directly.

Common pitfall

Confusing the OS with the shell, the desktop environment or the kernel alone is common. Programs that bypass abstractions or assume one OS become non-portable. Resource limits, permissions and scheduling policies from the OS can explain mysterious slowness or failures, so learn to inspect them with tools such as top and strace.

Where it fits in the course

What is an Operating System is topic 1 of 51 in Operating Systems, rated Beginner. It is the first topic in this area. The next topic is Kernel.

Practice and explore

How to study this topic

  1. Read the explanation above and restate the definition in your own words.
  2. Open the interactive lesson and answer its mini quiz.
  3. Read the common pitfall, then write a short example that avoids it.
  4. Check your understanding in the Operating Systems quiz, and revisit the topic if you miss a question.

Frequently asked questions

What is What is an Operating System?
Software managing hardware and providing services to programs. It belongs to Operating Systems and is a beginner-level topic.
Where do people use What is an Operating System?
Every laptop, phone, server, router and embedded device runs one, such as Linux, Windows, macOS, Android or an RTOS.
What is the most common mistake with What is an Operating System?
Confusing the OS with the shell, the desktop environment or the kernel alone is common.
What should I learn before this topic?
Nothing earlier in Operating Systems is required. This is where the area begins.
How can I practice it?
Answer the mini quiz in the interactive lesson, then take the Operating Systems quiz.
Is What is an Operating System hard to learn?
It is a Beginner topic, so it works as an entry point. If the terms are new, read the explanation twice and try the visualizer before the quiz.
How long does it take to learn What is an Operating System?
Most learners can read the explanation and finish the interactive lesson in under an hour. Fluency comes from applying the idea, so plan a few short practice sessions with the quiz.
Which topics are related to What is an Operating System?
Kernel, User Mode vs Kernel Mode, System Calls are closely connected. The full list is in the related topics section of this page.
What should I study after What is an Operating System?
Continue with Kernel, the next topic in Operating Systems.

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