This guide to the Japanese zodiac gives a complete explanation of all 12 animal years.
Like people of the West, Eastern people have a zodiac. Unlike that of the West, however, the Eastern system has a cycle of twelve years instead of months. Each year of the cycle has its own particular animal symbol whose roots of meaning, origin, and influence stretch back to ancient India and China.
One of the traditional Japanese stories pertaining to this zodiacal system and how it started runs as follows. On a certain New Year's Day, ages ago, Buddha called all the animals of the world to him. He promised that those who came to pay him homage would receive a gift for their fealty. As a mark of honor, they would be given a year which would thereafter be named for them. Of all the animals in the world, only these twelve came, and they came in this order: the rat and the ox, the tiger and the rabbit, the dragon, the snake, and the horse, the sheep and the monkey, the rooster, the dog, and the boar.