When you turn on your computer, a series of events occur before the operating system (OS) loads and you can access your desktop. This process is known as booting. Here's a general overview of the booting process:
1. BIOS/UEFI Initialization:
- When you power on your computer, the Basic Input/Output System (BIOS) or Unified Extensible Firmware Interface (UEFI) starts.
- BIOS/UEFI initializes basic hardware components like the keyboard, mouse, and display.
- It performs a Power-On Self-Test (POST) to check for any hardware issues.
2. Bootloader:
- Once the POST is completed, the BIOS/UEFI loads a small program called the bootloader.
- The bootloader searches for an operating system on available bootable devices (hard disk, SSD, USB, etc.).
3. Loading the Operating System:
- The bootloader reads the boot sector of the selected bootable device and loads the operating system files into memory.
- This includes essential kernel files and device drivers needed to start the OS.
4. Kernel Initialization:
- The operating system kernel, which is the core of the OS, begins to initialize itself.
- It configures system resources like virtual memory, process scheduling, and more.
5. Hardware Detection and Configuration:
- The kernel detects the hardware components connected to the computer and loads appropriate device drivers.
6. Creating System Processes:
- The kernel starts crucial system processes, such as the window manager, file systems, networking services, and more.
7. User Interface (Desktop) Loading:
- Once the necessary processes and hardware are configured, the graphical user interface (GUI) or desktop environment of your operating system loads.
8. Final Checks and Login:
- The operating system performs final checks and loads remaining user-interface elements.
- At this point, the computer is fully booted, and you'll be prompted to enter your user credentials if necessary.
After this process is completed, you gain access to your operating system's desktop or home screen, where you can interact with your applications, files, and other resources.