Yale romanization of Mandarin
The Yale romanization of Mandarin is a system for transcribing the sounds of Standard Chinese, based on the Beijing dialect of Mandarin. It was devised in 1943 by the Yale sinologist George Kennedy for a course teaching Chinese to American soldiers, and was popularized by continued development of that course at Yale.
Source: Wikipedia — Yale romanization of Mandarin (CC BY-SA 4.0)