Black box

Black box is a technical term for a device, system or object when it is viewed in terms of its input, output and transfer characteristics without any knowledge required of its internal workings. Almost anything might occasionally be referred to as a black box: a transistor, an algorithm, humans, the Internet.

The opposite of a black box is a system where the inner components or logic are available for inspection (such as a free software/open source program), which is sometimes known as a white box, a glass box, or a clear box.