Garbage In, Garbage Out

GIGO refers to Garbage In, Garbage Out. It basically means that poor quality input data will result in poor quality output data. That could involve data that is outdated, flawed, inexact, biased, incomplete, etc.

A good example to illustrate this principle is audio and video file. If the source of the recording is bad, so the quality of the numeric file will be (although errors can be identified and corrected by post-processing).