I'm pretty sure that's the POST or the Power On Self Test.
A computer is loading data when it is turned on and the operating system is being loaded.
Generally it's called "booting up" the system
operating system is not a loading, When is trun on system(press the power button). first of checked all the hardware devices,for exmple hard disk,ram,rom and etc. When the all devices dected process further. Jsb
first the booting files are loaded in the RAM and these files are in the boot sector where operating system is installed . after loading these file then these files load the operating system in the RAM , some portion of RAM is Allocated by the OS. after that window is ready to perform tasks.
booting
Booting up ..! A boot process is a step by step process with which a computer loads the operating system.
The bootstrap process is the sequence of actions that a computer system goes through when it is first turned on. It involves loading the operating system into memory and initializing the hardware components to prepare the system for use. The bootstrap process typically includes hardware diagnostics, configuration checks, and loading the necessary software components.
windows xp
When the computer is turned off, the operating system is not resident in memory; instead, it is stored on the hard drive or other storage media. Memory (RAM) is volatile, meaning it loses its contents when power is lost. Upon restarting the computer, the operating system is loaded from the storage into memory, allowing it to manage hardware and provide an interface for user applications.
When a computer is turned on, parts of the operating system are transferred from the hard drive (or other storage media) into the computer's RAM (Random Access Memory). This process is initiated by the BIOS or UEFI firmware, which performs hardware checks and loads the bootloader. The bootloader then loads the operating system kernel into RAM, allowing it to manage system resources and execute programs. Once loaded, the OS takes control of the computer, facilitating user interaction and application execution.
Safe-mode is an option for operating systems whereby many of the extra features are turned off so that one can investigate a problem. Therefore and operating system is required
The computer's hard disk stores data - be that the operating system, application programs, documents or virtual memory.Stores data that needs to be kept between times when the computer is turned off.