What Is an Operating System? What Really Happens When You Open an App

You click an app, and a window opens. Behind that simple action, your operating system creates a process, prepares memory, schedules CPU time, and coordinates hardware. How does it all work? In this beginner-friendly tutorial, we explain what an operating system is and what Windows, Linux, macOS, Android, and iOS do behind the scenes. An operating system (OS) manages the computer’s resources and provides the services applications need to run. Its core component, the kernel, controls critical resources and helps keep programs separated. In this video, you’ll learn: • Why applications usually access hardware through the operating system • What the kernel does and how it differs from the complete OS • How CPU scheduling lets programs share processor time • How memory management keeps applications organized and isolated • What a process is and how it differs from a program stored on disk • How file systems organize storage into files and folders • How device drivers connect the OS to hardware • How system calls let programs request kernel services • Why user mode and kernel mode matter for security • What happens when you launch an application • Why desktops, servers, phones, and embedded devices have different needs We also explain abstraction: how the OS hides complicated hardware details behind useful concepts such as files, processes, and virtual memory. Next in this series: What Is a Kernel? Subscribe to Gate & Kernel for clear, step-by-step explanations of how computers work—from logic gates to operating systems. #OperatingSystem #ComputerScience #HowComputersWork #OSExplained #Kernel #Linux #Windows #Programming #ComputerArchitecture #GateAndKernel 00:00 What Is an Operating System? 01:00 The OS as the Main System Software 01:48 Why Apps Don’t Control Hardware Directly 02:31 The Kernel: The Core of the OS 03:20 CPU Management and Scheduling 04:07 Memory Management and Protection 04:55 Programs vs. Processes 05:35 Files and Storage 06:16 Device Drivers Explained 06:55 OS Services and System Calls 07:37 Security: User Mode and Kernel Mode 08:21 Graphical and Command-Line Interfaces 09:01 What Happens When You Open an App? 09:44 Different Devices, Different Operating Systems 10:35 Resource Management and Abstraction 11:21 Conclusion and What’s Next