The Chinese New Year is the most important of the holidays for the Chinese. It is defined to be the first day of the first month in the traditional Chinese calendar. Unlike the Christian New Year, which is based on a solar calendar, the Chinese New Year is based on a traditional Chinese lunisolar calendar whose date indicates both the moon phase and the time of the solar year. A lunar month is around 2 days shorter than a solar month. In order to "catch up" with the solar calendar, an extra month is inserted every few years. This is why, according to the solar calendar, the Chinese New Year falls on a different date each year.
Normally, the celebration will start from the New Year's Eve and will last for around 15 days until the middle of the first month. Before the celebration, people will normally completely clean the house and display traditional New Year decorations. This festivity is the time for family reunion, which is the most important part of the Chinese New Year celebration. People will normally visit relatives and friends, do some shopping, watch traditional Chinese shows, launch fireworks, and plan for the coming year. The celebration will sometimes be highlighted with a religious ceremony given in honor of heaven, earth, the family ancestors and other gods. In modern China, working professionals will normally have 7 days of holiday including the weekend to celebrate. After the family reunion, some modern Chinese families may take the chance to visit tourist destinations.