A girl climbs a mountain with her grandma to enjoy the chrysanthemums during the Double Ninth Festival. [Photo/VCG]

The ninth day of the ninth month in the Chinese lunar calendar is a traditional Chinese festival — the Double Ninth Festival, or Chongyang Festival. In Chinese culture, nine has long been regarded as the number of "yang", making the day of the festival one of two "yang" numbers, while "chong" in Chinese means double - thus creating the name of the festival, Chongyang.

A traditional poem written by Wang Wei during the Tang Dynasty (618-907) is often quoted in relation to the holiday, which reads,

“As a lonely stranger in a foreign land, I pine at every holiday - my homesickness increases. Far away, I know my brothers have reached the mountain peak; They are wearing dogwood, but one is not present.”

Traditional customs of the festival include reaching a mountain peak and wearing dogwood just as in the poem, though many young people don't even know what dogwood looks like.

What does the Double Ninth Festival mean today? Why do people climb mountains and wear dogwood on this special day？Why is the festival celebrated as "Senior Citizens Day" now? Let’s explain, one at a time.