Chinese calendars have been around since 2600 BC. This makes the Chinese New Year the longest record of time in history. In fact, it is even the largest chronological record. It began when Emperor Huang Ti first introduced the cycle of the zodiac, which is still in place today. The Chinese calendar is actually quite similar to the Western calendar. Known specifically as the Chinese Lunar Calendar, it is a yearly record of time. As the name suggests, it is based on the cycles of the moon.
In Western calendar, as many of us know have different names for each month, the Chinese calendar is exactly the same, they just name their months after animals. Each animal represents one of the animals that visited Buddha before he left earth or at least that is how the story is told.
The Chinese zodiac is heavily linked to the Chinese calendar. The animals that are named after each month in the Chinese zodiac have been said to have an influence on people that were born in those years; for instance, a person with the dog Chinese zodiac tends to be very loyal.
A large part of the world's population is Chinese. Clearly, a lot of people thus also follow the Chinese calendar. It is mainly used to determine when that culture's celebrations, festivals, holidays, and special occasions occur. For everything else, the Chinese people actually follow the Gregorian calendar.
The zodiac is not the only thing which governs this calendar. Certain aspects of astronomy also play a part in it. Notably, the phases of the moon and the sun's longitude play a huge role in determining the Lunar calendar. As you might imagine, the system has thus been greatly influenced by certain aspects of science.
On one hand, the Lunar calendar bases its dates on the dates of the cycles of the moon. The cycles for the new moons are used specifically. Whenever the new moon occurs, it indicates a new month. The longitude of the sun is also used. It determines the Principal Terms of the Chinese calendar. Those in turn determine the actual numbers of each month.
A few things to keep in mind when you are dealing with Chinese Calendars; each year represents one animal, although in 2009, the year of the Ox occurs. This particular animal year only takes place every twelve years.