Bazi, based on the date recording system from Ancient China, is using the Tian Gan (天干) and Di Zhi (地支) to accurately record the year, month, day and time, the sixty combination of Tian Gan and Di Zhi formed an elemental cycle (六十甲子循環), the date are represented by the four pair of Tian Gan and Di Zhi or we called that the eight words of date recording.
The Ancient Chinese found that the eight words (also called "Bazi") of the recorded date which can also projecting the track of the person who borned on the date. The ten of Tian Gan (天干) and Twelve of Di Zhi (地支) are containing their owned different elements, supporting or against with each others. There are five groups of elements (五行) containing Wood, Fire, Earth, Metal and Water.
The Ong Metaphysics Group (OMG) formed in 2004, founded by Master Tommy Ong, developed a systematic method of Bazi Diagnostics Service:
i) Based on your characteristic of personality
ii) Look at your past (history and experiences)
iii) Focus on your steps (present situation and condition)
iv) Forecasting your future (consulting and advices for your future plans and goals)