What's the name of Lantern Festival? Why?

The fifteenth day of the first lunar month: Lantern Festival

(Also known as "Shangyuan Festival", that is, the fifteenth day of the first lunar month. This is an important traditional festival in China. In ancient books, this day is called Shangyuan, and its night is called Yuanye, Yuanxi or Yuanxiao. The name Yuanxiao has been used ever since. Because the Lantern Festival has the custom of decorating lanterns and watching lanterns, it is also called "Lantern Festival" among the people. In addition, there are customs such as eating Yuanxiao, walking on stilts and riddles. The ancient calendars in China were closely related to the phases of the moon. On the fifteenth day of each month, people will welcome the first full moon night of the year, which is naturally considered as an auspicious day. As early as the Han Dynasty, the fifteenth day of the first month has been regarded as a day of offering sacrifices to gods and praying for blessings. Later, the ancients called the fifteenth day of the first month Shangyuan, the fifteenth day of July Zhongyuan and the fifteenth day of October Xia Yuan. At the latest, in the early Southern and Northern Dynasties, Sanyuan was the day when grand ceremonies were held. Of the three elements, Shangyuan is the most valued. Later, the celebrations in the Central Plains and Xia Yuan were gradually abolished, but Shangyuan was enduring. )