Like BIOS, UEFI is installed at the time of manufacturing and is the first program that runs when a computer is turned on. It checks to see what hardware components the computing device has, wakes the components up and hands them over to the operating system. The new specification addresses several limitations of BIOS, including restrictions on hard disk partition size and the amount of time BIOS takes to perform its tasks.
Because UEFI is programmable, original equipment manufacturer (OEM) developers can add applications and drivers, allowing UEFI to function as a lightweight operating system.
The Unified Extensible Firmware Interface is managed by a group of chipset, hardware, system, firmware, and operating system vendors called the UEFI Forum.The specification is most often pronounced by naming the letters U-E-F-I.
Continue reading about UEFI:
Andrew Regenscheid, a mathematician with the computer security division of the National Institute of Standards and Technology (NIST), is concerned about the security issues UEFI presents.
Sebastian Anthony demystifies the long-overdue BIOS replacement.
Eric Parizo explains how NIST guidelines seek to minimize risk of BIOS attacks.
Microsoft's Steven Sinofsky describes how UEFI enables secure boot.