UEFI (Unified Extensible Firmware Interface)
UEFI (Unified Extensible Firmware Interface) is a specification that defines the interface between the operating system and the platform firmware. UEFI replaces the previous Basic Input Output System (BIOS) that was originally found on all IBM PC-compatible personal computers, but most UEFI implementations still in use today also support legacy BIOS features through the Compatibility Support Module (CSM).