The twelve zodiac animal signs are rat, ox, tiger, rabbit, dragon, snake, horse, goat (or sheep), monkey, rooster, dog and pig in that order. The legend had it that the rat was given the task to invite the animals to report to heaven to be selected for the zodiac signs. The cat was a good friend of the rat, but the rat forgot to invite him. So the cat vowed to be the rat's natural enemy for ages to come.

There is also a cycle of the five Chinese elements on top of the cycle of animals. The elements are Metal (Gold), Water, Wood, Fire, and Earth. So the year sign can be a gold dragon, a wood rooster etc. In ancient match-making practice in China, couples were brought together according to their compatible signs. For example, it is believed that dog and dog don't get along, but dog and pig do; a water dog supports a wood pig but dominates a fire pig in their relationship because water benefits wood, but controls fire according to the Chinese five elements' interaction.