UEFI

UEFI is a specification defining the interface between a computer’s firmware and its operating system. It provides a modern alternative to legacy PC BIOS, including standardized boot services and data structures.

UEFI boot process: The sequence in which UEFI initializes hardware, selects a boot target, and starts an operating-system loader. It shows how UEFI locates and launches an operating system before handing over control.
Firmware: Software embedded in a device that initializes hardware and provides low-level control. UEFI specifies an interface to the firmware that starts the operating system.
Secure Boot: A UEFI security feature that verifies digital signatures on boot software before allowing it to run. It uses UEFI policy and keys to block unauthorized boot components.
Legacy BIOS boot mode: A compatibility mode in which UEFI firmware starts a computer using legacy BIOS boot conventions. It lets modern firmware run older boot software that does not support native UEFI.
Intel Boot Initiative: Intel’s early effort to develop a modern firmware interface for its Itanium-based computers. Its work laid the foundation for the interface that became EFI and later UEFI.
UEFI Boot Manager: Firmware software that manages boot entries and selects which UEFI application or operating-system loader to run. Its boot entries let firmware choose among operating systems and removable-media loaders.
BIOS: The traditional PC firmware interface that initializes hardware and starts an operating system using legacy conventions. UEFI was designed as a more extensible successor to the legacy BIOS interface.
Network booting: Starting a computer from software or an operating-system image delivered over a network. UEFI can load network boot applications through firmware network protocols.
Master Boot Record: A disk-partitioning scheme whose first sector contains boot code and a table for four primary partitions. Traditional BIOS boot commonly relies on MBR boot code, unlike typical UEFI-and-GPT setups.
Extensible Firmware Interface: Intel’s firmware interface specification that preceded the industry-wide UEFI standard. UEFI developed from EFI after stewardship shifted beyond Intel.

Linked from 7 pages