ACPI(Advanced Configuration and Power Interface) is an industry specification for the efficient handling of power consumption in desktop and mobile computers. ACPI specifies how a computer's BIOS, operating system and peripherals communicate with each other about power usage. ACPI allows the following capabilities (assuming the operating system supports them): The user can specify at what time a device, such as a display monitor, is to turn off or on. The user of a notebook computer can specify a lower-level of power consumption when the battery starts running low so that essential applications can still be used while other, less important applications are allowed to become inactive. The operating system can lower the clock speed during times when applications don't require the full processor clock speed. The operating system can reduce motherboard and peripheral device power needs by not activating devices until they are needed. The computer can enter a stand-by mode when no one is using it, but with modem power left on to receive incoming faxes. Devices can be plug-and-play. As soon as plugged in, they can be controlled by ACPI. ACPI must be supported by the computer's motherboard, BIOS and the operating system. One of several power schemes can be chosen. Within a power scheme, the user can control the power to individual devices. In order for ACPI to work on your computer, your BIOS must include the ACPI software and the operating system must be ACPI-compatible. ACPI is designed to work with Windows 98 and with Windows 2000.

This definition is in context to Computer Hardware. See more contextual defintions for ACPI.