The Chinese New Year is now popularly known as the Spring Festival because it starts from the Beginning of Spring, the first of the 24jieqi. Its origin is too old to be traced. Several explanations are hanging around. All agree, however, that the word nian (year) was originally the name of a monster that started to prey on people the night before the beginning of a new year in accordance with the Chinese calendar.
One legend goes that the monster nian had a very big mouth that would swallow a great many people with one gulp. People were very scared. One day, an old man came to their rescue, offering to subdue nian. When n ian came, he said to it, "I hear that you are very resourceful, but can you swallow the other beasts of prey on earth instead of people who are by no means of your worthy opponents?" So, nian eliminated a great number of the beasts that had preyed on people and their domestic animals and drove what was left into the depth of forests and mountains.
Then, the old man mounted the beast and left. He turned out to be an Immortal. Now that nian was gone and other beasts of prey were also scared into forests, people began to enjoy their peaceful life. Before the old man's departure, he had told them to put up red paper decorations on their windows and doors, and burn bamboos to make cracking noises before a new year to deter nian from sneaking back, for red was the colour the beast feared the most.
The tradition of observing the conquest of the beast nian has been carried on from generation to generation. The term guonian, which originally meant "survive the nian" has gradually become "celebrate the (New) Year" as the word guo has a double meaning of "pass-over" and "observe." Today, the custom of pasting red paper (now couplets with words of good wishes) and firing fire-crackers is still going strong. However, people have long forgotten why they are doing all this, except that they feel the colour and the sound add a lot to the excitement of the New Year celebration.