Garbage In, Garbage Out

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garbage in, garbage out

[¦gär·bij ′in ¦gär·bij ′au̇t]
(computer science)
A phrase often stressed during introductory courses in computer utilization as a reminder that, regardless of the correctness of the logic built into the program, no answer can be valid if the input is erroneous. Abbreviated GIGO.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

Garbage In, Garbage Out

(GIGO) /gi:'goh/ Wilf Hey's maxim expressing the fact that computers, unlike humans, will unquestioningly process nonsensical input data and produce nonsensical output. Of course a properly written program will reject input data that is obviously erroneous but such checking is not always easy to specify and is tedious to write.

GIGO is usually said in response to lusers who complain that a program didn't "do the right thing" when given imperfect input or otherwise mistreated in some way. Also commonly used to describe failures in human decision making due to faulty, incomplete, or imprecise data.

The expansion "Garbage In, Gospel Out" is an ironic comment on the tendency to put excessive trust in "computerised" data.
This article is provided by FOLDOC - Free Online Dictionary of Computing (


(Garbage In Garbage Out) "Bad input produces bad output." Data entry is critical. All possible tests should be made on data entered into a computer.

"Garbage In, Gospel Out"

An alternate meaning. Many people have too much faith in computer output!

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