UEFI

(Unified Extensible Firmware Interface) A standard programming interface for booting a computer. Governed by the UEFI Forum (www.uefi.org), it evolved from the EFI interface developed by Intel and first used in its Itanium line. Designed to replace the BIOS startup system, UEFI is also compatible with older BIOS-based machines.

PCs began to ship with UEFI in 2006, and Microsoft support began with the 64-bit versions of Windows Server 2008 and Vista Service Pack 1 (SP1). Most Windows, Mac and Linux versions support UEFI, but not all of its features. Starting with Windows 8, Windows supports UEFI's secure boot feature.

UEFI Is Software Based
Whereas all BIOS routines are stored in firmware, UEFI resides in a folder in flash memory on the motherboard or on the hard drive or network drive. The U in UEFI means any platform can be supported by recompiling the boot code, and the E in UEFI means functions can be added and enhanced, because its size is not limited to a firmware chip.

A Lower-Level Operating System
Residing between the computer's firmware, which starts the boot process, and the OS, UEFI is able to detect malware, as well as perform encryption, authentication and diagnostic functions, at a level lower than the OS. UEFI can reside stand-alone or be invoked after a BIOS-based machine performs its power on self test (POST) and hardware setup. See BIOS and GPT.