So what is Dong zhi? I only know I had to eat tang yuan(marble-shaped glutinous rice ball) on this day, so i did a bit of research and here it goes:
The DONG ZHI is based on the solar term of the solar calendar, which is in this case, the 22nd solar term known also as dong zhi. It coincides with December 22 of the Gregorian calendar and perhaps sometimes it falls on the 21st or 23rd December but it was very rare. Dong Zhi is the thanksgiving of the Chinese calendar. "Dong Zhi" literally means "arrival of winter". Coinciding with the winter solstice, it is an occasion for the family to get together to celebrate the good year they have had. Tang Yuan is cooked and eaten to symbolise unity and harmony within the family. Dong Zhi occurs 6 weeks before Chinese New Year and would normally fall between 21st Dec and 23rd Dec.
Tang Yuan in chinese sounds like "reunion". Yuan, which means “round” or “a circle”, is also an auspicious word that suggests perfection.
There is also another saying that goes "Chi tang yuan, da yi nian (Eat tang yuan and grow older by a year).”
So, make yourself at home, enjoy eating these delicious Tang Yuan! ^^ Wishing everyone happy Dong Zhi!~!