Background knowledge

• Universal Serial Bus (USB): versions ^{(local copy)} and specifications.
  
  
• Master boot record (MBR): https://en.wikipedia.org/wiki/Master_boot_record
  
  
• GUID Partition Table (GPT): https://en.wikipedia.org/wiki/GUID_Partition_Table
  
  
• GNU GRand Unified Bootloader (GRUB): https://en.wikipedia.org/wiki/GNU_GRUB
  
  
• Basic Input/Output System (BIOS): https://en.wikipedia.org/wiki/BIOS
  
  
• Unified Extensible Firmware Interface (UEFI): https://en.wikipedia.org/wiki/Unified_Extensible_Firmware_Interface
  
  
• Some notes about (U)EFI v.s. BIOS
  https://askubuntu.com/questions/927924/how-to-install-ubuntu-in-uefi-mode
  See the links under the first response:
  
  • Adam Williamson's blog entry on how EFI works -- This page describes the theory behind EFI-mode booting.
    https://www.happyassassin.net/2014/01/25/uefi-boot-how-does-that-actually-work-then
  • A question and answers on the differences between BIOS and EFI booting on Superuser.com -- This provides the basics of the preceding, but is more concise.
    http://superuser.com/questions/496026/what-is-the-difference-in-boot-with-bios-and-boot-with-uefi
  • Installing Linux on EFI systems -- This page is a more practical introduction to EFI-mode booting than Adam Williamson's blog.
    http://www.rodsbooks.com/linux-uefi/
  • Rod Smith's page on the CSM -- This page covers the CSM, including when it's useful and when it's not.
    http://www.rodsbooks.com/efi-bootloaders/csm-good-bad-ugly.html
  • The Ubuntu community wiki entry on UEFI -- This page is a bit disjointed, but is the most Ubuntu-specific introduction to EFI and its issues.
    https://help.ubuntu.com/community/UEFI

If you accidently overwrote the boot loader of Windows (UEFI) during installation of Linux

• See the link to recover the boot loader of Windows (UEFI).^{local copy}