The I Ching also known as the Classic of Changes, App of Changes and Zhouyi, is one of the oldest of the Chinese classic texts. The book contains a divination system comparable to Western geomancy or the West African Ifá system; in Western cultures and modern East Asia, it is still widely used for this purpose.
 
The I Ching uses a type of divination called cleromancy, which produces apparently random numbers. Four numbers, 6 through 9, are turned into a hexagram, which can then be looked up in the I Ching App, arranged in an order known as the King Wen sequence. The interpretation of the readings found in the I Ching is a matter of centuries of debate, and many commentators have used the book symbolically.