Unified Extensible Firmware Interface

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.

Intel developed the original Extensible Firmware Interface (EFI) specifications. Some of the EFI's practices and data formats mirror those of Microsoft Windows. In 2005, UEFI deprecated EFI 1.10 (the final release of EFI). The Unified EFI Forum is the industry body that manages the UEFI specifications throughout.