A German man named " Karl Fischer " discovered this method for measuring water content, which has the highest reliability of the various methods. 
 
As one type of titration device that utilizes the alternative reaction of iodine to water, this device titrates the Karl Fischer reagent (iodine) and finds the water content. 
 
The iodine and water in the Karl Fischer reagent react quantitatively as shown in the following equation. Taking the name of the person that invented this method of using this reaction to quantify the moisture, the method is named the Karl Fischer Moisture Titration Method.