Advanced Configuration and Power Interface

In computing, the Advanced Configuration and Power Interface (ACPI) specification provides an open standard that operating systems can use to perform discovery and configuration of computer hardware components, to perform power management by, for example, putting unused components to sleep, and to perform status monitoring.

First released in December 1996, ACPI defines platform-independent interfaces for hardware discovery, configuration, power management, and monitoring, and is designed to replace Advanced Power Management (APM), the MultiProcessor Specification, and the Plug and Play BIOS (PnP) Specification. ACPI brings the power management under the control of the operating system, as opposed to the previous BIOS-centric system that relied on platform-specific firmware to determine power management and configuration policies. The specification is central to the Operating System-directed configuration and Power Management (OSPM) system, an implementation for ACPI which removes device management responsibilities from legacy firmware interfaces via a UI.

Internally, ACPI advertises the available components and their functions to the operating system kernel using instruction lists ("methods") provided through the system firmware (UEFI or BIOS), which the kernel parses; and then executes the desired operations (such as the initialization of hardware components) using an embedded minimal virtual machine.

Intel, Microsoft and Toshiba originally developed the standard, while HP, Huawei and Phoenix also participated later. In October 2013, the original developers of the ACPI standard agreed to transfer all assets to the UEFI Forum, in which all future development will take place.

...
Wikipedia