Booting is the process of starting up a computer and loading the operating system (OS) into its main memory (RAM) so that the computer becomes ready to use.
Key Stages of Booting:
- Power-On (Hardware Check)
- When you turn on the computer, the Power Supply Unit (PSU) sends electricity to the motherboard and other components.
- The Basic Input/Output System (BIOS) or Unified Extensible Firmware Interface (UEFI) firmware runs a Power-On Self-Test (POST) to check hardware (CPU, RAM, storage, etc.).
- Bootloader Execution
- The BIOS/UEFI looks for a boot device (HDD, SSD, USB, or network) based on the boot order.
- It loads a small program called the bootloader (e.g., GRUB for Linux, Windows Boot Manager) from the boot device.
- Operating System Loading
- The bootloader loads the kernel (core of the OS) into memory.
- The kernel initializes drivers, mounts filesystems, and starts essential system processes.
- User Login
- Once the OS is fully loaded, a login screen or desktop environment appears, allowing the user to interact with the system.
Types of Booting:
- Cold Boot: Starting the computer from a completely powered-off state.
- Warm Boot (Restart): Rebooting the system without cutting power (e.g., via software).
- Fast Boot (UEFI Feature): Skips some POST checks to speed up startup.
Common Issues During Booting:
- No POST beep/display: Hardware failure (RAM, GPU, PSU).
- “Operating System Not Found”: Corrupted bootloader or missing OS.
- Infinite boot loop: Software or driver conflicts.