Chinese New Year (Nónglì Xinnián), also known as the Lunar New Year is the most important of the traditional Chinese holidays.  It is celebrated on the first day of the first month of the Chinese calendar, i.e. the day of the second new moon after the day on which the winter solstice occurs, unless there is an intercalary eleventh or twelfth month in the lead-up to the New Year—in such a case, the New Year falls on the day of the third new moon after the solstice (the next time this occurs is in 2033).  The Chinese New Year period also known as Spring Festival unofficially starts on on 23rd day or 24th day of the 12th month of the lunar calendar and ends with the Lantern Festival, on the fifteenth day of the First month of the New Year (which is a full moon).

The Orgin of New Years and the legend of Nian
The Chinese word Nian means ripe grains.  The word dates back to oracle bone inscriptions dating back three thousand years ago.  A good harvest or the process of a harvest was considered a year.  The whole purpose, in history, of creating a calendar or keeping track of time was to facilitate agriculture.  It was important to know when to till the soil and sow the seeds.  You can say that the first calender in China was sort of put together for the benefit of agriculture production.  In the Zhou Dynasty the year was formally called "nian" and the beginning of the year was called “suishou” .  In 104 BC, Emperor Liu Che of the Western Han Dynasty presided over the formulation of the solar lunar calendar which is simular to the Hebrew Caledar.

Since the beginning of the Han Dynasty, New Years Day and Winter Solstice were the emperor’s most important times.  It was the responsibility of the emperor to keep track of the time, to perform traditional rituals before these dates, and tune and select the music so that heaven and earth were in harmony.  Winter Solstice was the most important event because if an emperor blundered that day the kingdomn wouldn't know which day marked the coming of the new year.  These two days are the only days that don’t change on the lunar calendar.

The festival was a way of letting the people know what time it was and what to do. The lunar calendar had all sorts of important days that kept people in tune with their daily rituals and mother nature.  Keep in mind that the emperors did not do everything by themselves and had experts or “officials” to help out, but they were responsible to keep the mandate.  By insuring the accuracy of these dates, the state and the people new when to work and when to do what (the lunar calendar is like the farmers almanac).

Besides historical records, there are also many stories and legends worth mentioning.  The  first and most enjoyable is the story of Nian (Year "Nian" as in New Year –"Xin Nian").  There was a monstor in ancient times with a body of a bull and the head of lion.  It was a ferocious animal that lived in the mountains and hunted for a living.  Towards the end of winter when there was nothing to eat it would visit the villages and attack and eat whatever it could.  The villagers would live in terror over the winter.  Over time the villagers realized that the ferocious Nian was afraid of three things: the color scarlet, fire, and noise.  The villagers came together and agreed that when it was time for Nian's annual visit towards the end of winter they would start a fire in front of every door, hang a board painted scarlet in front of every house, and not go to sleep but rather make noise. 

 So one night when Nian was spotted coming down the mountain they started the fires, put up the boards, and stayed up all night long making noises.  The monster came down saw and heard the ruckess, freaked and ran into the mountain never to return.  The next morning everyone got up congratualated eachother and had a big celebration.  The next year they repeated the ritual and it has been passed down generation to generation and the custom of guonian was thus established.