The boot process is the procedure that the system follows when initializing the system from when you press the ON button to that time when it becomes usable.
At a passive point of view, the whole matter might be trivial and unimportant. But thinking about it again will tell you that it is not so at all. After all, if your computer didn’t boot up, you might be in for a whole lot of trouble.
You don’t have to learn it very hard. Nevertheless, a good understanding of the boot process can save you from a lot of headaches when troubleshooting problems. Also, knowing it better will help you tailor-fit your computer to your own needs.
[LFS101.x Chapter 03, Section 2: The Boot Process]
sysadminthings 
Very good point! The boot process is important when troubleshooting systems that won’t boot. The first step all computers go through is the Power-On self-tests (POST) check. This is when the computer checks to see what kind of hardware is connected to it (keyboard, monitor, hard drives, etc).
After POST the computer checks to see which hard drive is the ‘master’, and passes in the location of the boot sector of the master hard drive to the CPU which begins execution from that sector. This will, in most cases, load your boot loader which is Grub in the Linux world nowadays.
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