Unified Extensible Firmware Interface (UEFI) is a software interface that is used between the operating system and platform firmware. It is designed to replace the traditional BIOS firmware interface and provide advanced features such as support for large disks, network booting, encryption, and more. UEFI is a specialized skill that entails knowledge of firmware and operating system architecture, programming languages, and debugging tools. UEFI experts are in high demand for system development, firmware development, and security-related roles in companies that develop hardware and software products.