There is a folklore about Double Seventh Day widely spread among Chinese people. It was said that there was a beautiful girl named the Weaver Girl, who was a daughter of the Emperor of heaven, living at the east of the Milky Way. She sat beside the loom every day, weaving the wonderful scene like the beautiful morning glow and the magnificent sunset. She was so busy and therefore had no time to dress up herself. The emperor of Heaven took pity on her and introduced the Niulang, who lived in the west of the Milky Way, to her. They fell in love with each other and got married. However, Weaver Girl gradually gave up the textile work as falling into marital life after marriage, which made the Emperor angry. As a result, he made an order that Weaver Girl must back to the east of the Milky Way and more importantly, the couple was allowed to meet only once year on the 7th July of lunar month. In the dead of night when lying prone under the grape trellis can listen to their whisper.
Every year on the seventh day of autumn, we always notice that magpies with fewer feathers on their heads. As the story told us, magpies gather at the milky river that day, lining a bridge with their head for Niulang and Weaver Girl’s meeting, as a result, their feathers on heads were trampled bald. There is another saying that magpies would use Five-color thread that people wore in Dragon Boat Festival to make a rainbow bridge for the sweet couple.
In China, although there are many different versions of the story, what remain the same was people’s praise of love, and yearn for a happy marriage life.
In fact, the Double Seventh Day was not started with the theme of love, with the widely spread of the love story, it started to known as Chinese Valentine’s Day. Initially, the Double Seventh Day was a festival exclusively for girls, also called Girls’ Day or Qi Qiao Day. On this day, girls would dress up themselves and pray to Weaver Girl for wisdom, beauty, skill and love. After the ceremony, girls would take colored thread and pass it through the needle’s hole, who could pass seven needle could be called DeQiao (have skillful hands), otherwise, they were called Shu Qiao (miss skillful hands). After the Double Seventh Day, girls would exchange their handicrafts with friends. And one distinctive food in Double Seventh Day was Qiao Guo, which was made from flour, oil, sugar and honey. Some girls would knead a variety of patterns related to the story as well.
 乞巧的來歷和風俗 https://wannianli.tianqi.com/news/268507.html