How does UEFI work?

Question

I was studying about bootloaders when exactly came upon the term UEFI. I can understand some things about UEFI. But still, In what mode(Real,Protected,Long) does a system wi

Answer 1

If you wish to know more about how UEFI works then the post UEFI boot: how does that actually work, then? by Adam Williamson is highly recommended.

He answers the questions you have and its a good read:

Now let’s look at how booting works on a UEFI system. Even if you don’t grasp the details of this post, grasp this: it is completely different. Completely and utterly different from how BIOS booting works. You cannot apply any of your understanding of BIOS booting to native UEFI booting. You cannot make a little tweak to a system designed for the world of BIOS booting and apply it to native UEFI booting. You need to understand that it is a completely different world.

The Wikipedia page Unified Extensible Firmware Interface is also a useful resource.