The I Ching 64 hexagrams are formed by the combination of 8 trigrams (three lines). 2 trigrams are paired up with one trigram on the top and one at the bottom. The paired trigrams become one hexagram (six lines).
In pinyin, I Ching is written as Yijing.
Each hexagram has its own meaning. In the art of Chinese naming, the number of strokes in the name can be converted to one of these hexagrams. Then, referring to the particular hexagram, we can make a forecast of the person's luck.
In advanced Yijing Plum Blossom divination method, the I Ching 64 hexagrams are used for telling the past and forecasting the future. It is really an amazing book for those who know how to use it.