Put simply, calibration is the correcting or initial setting of a measuring device by adjusting that device to match a known and unchanging measurement. Correct calibration ensures that the readings offered by measuring devices like scales, thermometers, and lab instruments are accurate and reliable.
Just as common items like cars and computers experience wear and tear over time, sophisticated instruments used in sectors such as telecommunications or the bio-medical industry experience changes over time. These changes – whether they arise from normal use or some form of misuse – eventually impact the accuracy of these instruments and bring about the need for instrument calibration. This need for calibration is particularly important in highly sophisticated instruments in which multiple measurements are mutually dependent.