What is the eight characters? Eight words, not many words. This is not the answer!
Birth date or constellation refers to the time when a person was born, that is, year, month, day and hour. People use heavenly stems and earthly branches to express year, month, day and hour respectively, such as Jiazi Year, Shen Bingyue, Xin Chou Day, Ren Yin Shi and so on. The year, month and day are expressed in two words each, adding up to eight words, from which the eight characters come.