The online free八字 (Ba Zi) fortune-telling, also known as the birth time fortune-telling, is based on the year, month, day, and hour of a person's birth. According to China's traditional method of counting using the Celestial Stems and Terrestrial Branches, the Heavenly Stems and Earthly Branches at the time of birth are arranged into a combination of eight characters, which is also called the "birth time八字 (Ba Zi)."