In ancient times, time was recorded using the heavenly stems and earthly branches. It's the so-called eight characters.
The counting period is 60, and the year, month, day and time are 60 units each.
For example, the time when I reply to you is Xinwei day of Bingshen month in Bingshen year and Yihai hour.
Note: A day is divided into 12 hours. At first, day and night were divided into one hundred quarters, and by the early Qing Dynasty, it was divided into ninety-six quarters. According to the Qing Dynasty's calculation of 96 quarters, one quarter is 15 minutes.