Overview #Unified Extensible Firmware Interface (UEFI) is a specification by the Unified EFI Forum that describes an interface between the Operating System (OS) and the platform firmware.
Unified Extensible Firmware Interface is in the form of data tables that contain platform-related information, and boot and runtime service calls that are available to the OS loader and the OS. Together, these provide a standard environment for booting an Operating System. This specification is designed as a pure interface specification. As such, the specification defines the set of interfaces and structures that platform firmware must implement. Similarly, the specification defines the set of interfaces and structures that the OS may use in booting. How either the firmware developer chooses to implement the required elements or the OS developer chooses to make use of those interfaces and structures is an implementation decision left for the developer.
Unified Extensible Firmware Interface replaces the Basic Input-Output System (BIOS) firmware interface originally present in all IBM PC-compatible personal computers, with most Unified Extensible Firmware Interface firmware implementations providing legacy support for BIOS services.
Where BIOS interfaces require the OS loader to have specific knowledge of the workings of certain hardware devices the Unified Extensible Firmware Interface specification provides Operating System loader developers with abstracted interfaces that make it possible to build code that works on a range of underlying hardware devices without having explicit knowledge of the specifics for each device in the range.
Unified Extensible Firmware Interface can support remote diagnostics and repair of computers, even with no operating system installed
Unified Extensible Firmware Interface is an enhancement of the Intel developed the Extensible Firmware Interface (EFI) specification. Some of the EFI's practices and data formats mirrored those from Microsoft Windows. In 2005, UEFI deprecated EFI. The Unified EFI Forum is the industry body that manages the UEFI specification.