History

• The Chinese calendar is the oldest functioning calendar in the world, used for at least 4,000 years. The Gregorian calendar is the calendar used in the West and in most of the world (including China). It was invented in 1582 by Pope Gregory, replacing the shoddy Julian calendar used since Roman times. As the Europeans colonized the world, the Gregorian calendar spread. In the early-20th century, the Chinese government officially abandoned its calendar for the Western one, although the Chinese calendar is still observed by many.
  
  

Lunar versus Solar

• The Gregorian calendar, like most Western calendars that preceded it, focuses on the movement of the sun. It also is concerned with the date of Easter, which is based on the vernal equinox. By plotting the solar year, the calendar's months fall in line with the seasons. The Chinese calendar is solar and lunar, using both the sun and moon as guideposts. Early Chinese astrologers used the apparent motion of the sun, moon and stars to calculate their time cycle.
  
  

Years

• The Gregorian year is 365 days divided into 12 months. There isn't a pattern concerning how many days per month, and the actual day of the week of a date varies from year to year. The Chinese calendar is based on a 60-year cycle; each year is given a specific name and number, then is repeated. The year is split into 24 months of two weeks each. The Chinese New Year varies depending on the lunar cycle, usually happening in early February for the Gregorian calendar. The New Year for the Gregorian calendar is always January 1.
  
  

Application

• The Gregorian calendar is easy to calculate and mostly accurate, although it has its fair share of imperfections (leap years, for example, or the inconsistent matching of dates and days of the week). Requiring charting and calculations, the Chinese calendar is mostly a ritual document nowadays, used to figure out holidays and celebrations. The Gregorian calendar is the international standard and the Chinese have converted. However, because it's a lunar-based calendar, it helps with figuring out tides.