Black Box

n. safety device in airplanes which records flight statistics

Black box is a technical term for a device or system or object when it is viewed primarily in terms of its input and output characteristics. 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. Points of view such as interactive computation may see the concept of a black box as a useful fiction.
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Noun
1. equipment that records information about the performance of an aircraft during flight
(hypernym) recorder, recording equipment, recording machine

<jargon> An abstraction of a device or system in which only its externally visible behaviour is considered and not its implementation or "inner workings".
See also functional testing.
(1997-07-03)

a colloquial term for an electronic TV audience measurement system; an audiometer; a "people-meter".