BaZi is a system of deciphering destiny and luck. It was founded by astrologer Li Xu Zhong during Tang dynasty and further developed by Zi Peng (子平) during Song dynasty. The system of BaZi today is the result of refining the work of Zi Peng over the years.
The word BaZi means eight characters in Chinese. It is simply a person's date and time of birth expressed in eight special Chinese characters using the solar calendar system. The eight characters are usually expressed in four pillars (i.e. four columns) of characters; as a result, BaZi is also known as four Pillar. The four pillars represent the qi (i.e. cosmic energies) of the year, month, day and hour at the moment of birth.
A BaZi has two components. It has a destiny component (命盤) and a big luck component (大運). The destiny component is represented by the eight characters of a BaZi. The destiny component holds the code to a person's destiny. Analyzing the destiny component reveals what destiny indicates about affinities for friends, siblings, father, mother, talent, wealth, career, marriage, etc.
The second component is the big luck component. The big luck component is a series of two characters arranged in pillar form. Each pillar represents the qi in a 10-year period. The big luck component holds the code to a person's luck. Analyzing the big luck component and its interactions with the eight characters reveals how a person's luck changes through time.
According to BaZi studies, a person's fortune depends on destiny and luck component. Both components play important role in a person's fortune. An analogy of a person's life journey is a car on a long journey. Whether the journey (i.e. life journey) is good or bad depends on the car condition (i.e. destiny) and the road condition (i.e. luck). The journey will be smooth if the car condition is good and the road is not bumpy. The journey will be bumpy if the car condition is no good and the road is bumpy.