The Chinese zodiac consists of twelve animals, rather than the solar signs used in the west. In the Chinese calendar each period lasts for a full cycle of the moon, from new to full. There are twelve complete lunar cycles in a Chinese zodiac year, but one animal symbolizes the entire year. According to their calendar, the Chinese complete a cycle every twelve years. So if you were born in the year of the rat, you would celebrate your zodiac birthday every twelve years, and your Chinese zodiac sign would be the rat. In the west your astrological sign appears once each year.

The calendar and its animals were created from an ancient legend. It tells us that the animals were all fighting about who was going to be in the prime (first) position on the Chinese calendar. The gods devised a test in which the animals would compete for their position by swimming across a river. Another version says that the Buddha requested visits by the animals before he left earth. He named the moon cycles after the animals in order of appearance. So the Chinese zodiac symbol is a circle divided into twelve equal sections; think of it as if you were marking off slices of a pie. There is a picture of the animal representing that Chinese zodiac sign in each section. The calendar's use dates clear back to 2600 BC.

The animals used in Chinese astrology are rat, ox, tiger, rabbit, dragon, snake, horse, sheep (goat), monkey, rooster, dog, and boar (pig). Persons born during their cycle are said to take on their animal traits:

Chinese Zodiac - http://www.birthday-horoscopes.net/chinese-zodiac-signs.htm