What are the characteristics of birthdays?

Birth refers to heavenly stems and earthly branches in the year of life, heavenly stems and earthly branches in the month, heavenly stems and earthly branches in the day and heavenly stems and earthly branches in the day. It is eight words. For example,-Lunar calendar 19 19 in January 19 was born at 12, and19 is one year old, which is heavenly stems and not earthly branches. The first month is Bing Yin Yue. . . The perpetual calendar can be found!