The Chinese horoscope has been in use in the Orient for thousands of years, and it is still consulted by millions of people on a daily basis. Its twelve animal signs are similar to the twelve signs of the Western Zodiac, but are determined by the year you were born rather than the month.
Chinese astrology is based on the lunar cycle, which takes twelve years to complete.

Chinese astrology includes five elements instead of four -- Metal, Water, Wood, Fire and Earth. They are agents/modifiers that subtlely alter the nature of whatever they represent.

Yin and Yang -- The terms given to the complementary, dynamic forces that keep the universe in balance at every level.
The naming of the twelve years in the Chinese Lunar cycle stems from the myth of Buddha. Before leaving this world , Buddha invited all the animals of the world to a feast. Only twelve animals arrived, in the following order -- The rat, the ox, the tiger, the rabbit, the dragon, the snake, the horse, the goat, the monkey, the rooster, the dog and the pig. Thus, Buddha decided to name a year after each of them, in the order of their arrival. Each year in this twelve-year cycle now had a symbolic animal, whose characteristics were said to influence the world events, personality and fate of everything and everyone born in that year.