When talking about OS reinstallation, generally we would think of using CD/DVD or USB flash drive. But if our computer does not equip with a built-in CD/DVD-ROM (because they are already outmoded), and we have no pendrive (a bit difficult to make and use) or mobile HDD in hand, what then?
UEFI is unknown for most PC users, to fully understand it, you can use Google. Or you can also simply see it as a substitute of BIOS, which is much more advanced than the latter. However, the appearance of this new thing has brought many new problems to "Windows + Linux" dual systems. Fortunately, EasyUEFI can help us.