Chinese astrology is based around 12 animal signs, including the horse, the tiger and the dragon. Each year is associated with a different animal, and some astrologers believe that a person's basic characteristics are affected by the animal associated with his birth year.
When a person is about to make a major decision, such as a marriage proposal, he may check his birth year's animal against that of his partner to predict whether the decision is right. In an arranged marriage, the prospective couple's families may place great significance upon their children's respective animal signs.
Some scholars believe that the animal astrology was brought to China from central Asia, similar to the way Buddhism was introduced. Others believe that nomadic tribes in ancient China created the calendar based on the animals they hunted throughout the year. Astrology was important to the Chinese emperors, as they were considered responsible for everything under heaven.
Because each year is associated with a certain animal, and the cycle repeats every 12 years, it is possible to calculate a person's age by asking what animal sign he was born under. For example, someone born in the year of the dragon may have been born in 1988, 2000 or 2012.