Garbage In, Garbage Out

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Garbage In, Garbage Out (abbreviated to GIGO) is an aphorism in the field of computer science. It refers to the fact that computers, unlike humans, will unquestioningly process the most nonsensical of input data and produce nonsensical output. It was most popular in the early days of computing, but has fallen out of use as programs have become more sophisticated and now usually have checks built in to reject improper input.

GIGO is usually said in response to users who complain that a program did not "do the right thing" when given imperfect input. The first example of this was probably cited by Charles Babbage, inventor of the first programmable device who said:

On two occasions I have been asked,—"Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?" [...] I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question.^[1]

It is also commonly used to describe failures in human decision making due to faulty, incomplete, or imprecise data. For example, a poorly typeset TeX document will look bad because the user did not write the TeX source well.

Another, more recent, meaning of GIGO is Garbage In, Gospel Out. This phrase is a sardonic comment on the human tendency to accept the results from computer systems with unquestioning faith. An example of this blind-faith GIGO mentality is to believe that your work, stored in a computer, will be there whenever you need it even though you never perform data backup.

It can also be used as an explanation for the poor quality of a digitized audio or video file. Although digitizing is the first step in cleaning up a signal, it does not, by itself, improve the quality. Defects in the original analog signal will be faithfully recorded, but may be identified and removed by a subsequent step. See Digital signal processing.

[edit] Non-computer-related use of the term

The term can be used in any field in which it is difficult to create a good result when given bad input. For example, in translation, it is difficult to convert a source text that is confused, illogical or missing pertinent information into a quality translation. A translator use the phrase "Garbage in, garbage out" to explain the importance of good source text to a client.