UEFIs

UEFIs are the Unified Extensible Firmware Interface standards and their software implementations that serve as the low-level interface between a computer's hardware and its operating system. Developed as a modern replacement for the traditional BIOS, UEFIs are used by most contemporary personal computers and many embedded systems. A device's firmware can include a boot manager, device drivers, and an operating-system loader all operating within the UEFI environment.

The project originated at Intel in the 1990s as EFI and evolved into the Unified Extensible Firmware Interface standard. In 2006 the industry formed the UEFI Forum to coordinate revisions and guide certification. Over time, major hardware makers and operating system vendors adopted UEFI, with Apple and PC manufacturers shipping UEFI-based firmware and major OSes providing UEFI-compatible boot paths.

Key features of UEFIs include a modular driver model that runs in the pre-boot environment, support for the GUID Partition Table (GPT) instead of MBR, a built-in boot manager and shell, and runtime services that persist after the OS loads. Secure Boot provides cryptographic verification of bootloaders and drivers. UEFIs can support network boot (PXE or HTTP-based) and firmware update mechanisms such as Capsule updates.

Compared to BIOS, UEFIs generally offer faster startup, larger and more flexible disk support, graphical user interfaces, and easier extensibility. Most implementations provide a Compatibility Support Module (CSM) to preserve legacy BIOS compatibility for older operating systems and hardware.

Today, UEFI is widely deployed in desktops, laptops, and servers. Windows and many Linux distributions rely on UEFI for installation and operation; Secure Boot is enabled by default on many systems. Bootloaders such as Windows Boot Manager, GRUB, and systemd-boot run within the UEFI environment.

Challenges include securing firmware against attacks and ensuring reliable updates across diverse vendor implementations. The architecture favors standardization and interoperability but requires careful handling to maintain system integrity.