The term “Booting” refers to the process in which your computer runs a set of instruction when the power is switched ON. This process loads the Operating System into the computer main memory. Once after this has been done, you can able to see the windows desktop and run applications.
What happens during the booting?
Note: I’ve given an general overview of booting process. The process may change for different operating systems.
1. When you switch ON your computer, the BIOS software is built into the computer through a ROM (Read Only Memory), is the first code run by a computer.
2. When the computer starts up, the first job for the BIOS is the Power-On-Self-Test (POST), which initializes and identifies system devices such as the CPU, RAM, video display card, keyboard and mouse, hard disk drive, optical disc drive and other hardware.
3. If everything is fine, then BIOS locates, MBR (Master Boot Record) present in the hard disk. This MBR is written when the Windows is installed to your computer.
4. Master Boot Records contains information, whether a disk is bootable and the instructions to load the operating system. It loads the MBR data in a specific RAM space and then starts to load Operating System, giving the control to it.
This process is known as booting, or booting up, which is short for bootstrapping.
Types of Booting
There are two types of Booting.
1. Cold Booting: When you are booting your computer after shutdown, then it is know as Cold Booting.
2. Warm Booting: When you restarting your computer, then it is called as Warm Booting.
You might also heard about Rebooting, Rebooting refers to Warm Booting, in which all the Operating System files are loaded again.
Why do many applications ask for a reboot after a successful installation?
This happens when you install some major applications. These applications require some services and the files to run in the background for the applications to run. But last time when you booted your system, Operating System is unaware of the application and not started the required services or the files in the background.
So, in order to run those services required by the applications, a Reboot is required so that the operating system to load the file and to start the services.
What happens if Windows is not installed?
In this case, the MBR of the hard disk will be empty. Then, BIOS will look out for other devices to Boot (CD drives, USB drives) in the priority order that you have mentioned, and loads it. Check How_to_Boot_from_CD for changing the boot priority order and to boot from CD.
If it cant able to find MBR on any of removable devices, it will throw an error message and then halt the booting process.