The Unified Extensible Firmware Interface (UEFI) is a specification that defines a
software interface between an operating system and platform firmware. UEFI
replaces the legacy Basic Input/Output System (BIOS) firmware interface
originally present in all IBM PC-compatible personal computers, with most UEFI
firmware implementations providing support for legacy BIOS services. UEFI can
support remote diagnostics and repair of computers, even with no operating
system installed. ..... In November 2017, Intel announced that it planned to phase
out support for CSM by 2020.