In-laws are the names that parents of married men and women call each other's parents. Call male in-laws and female in-laws
The title of "in-laws" first began in the Tang Dynasty. "The Biography of Xiao Song in the New Tang Dynasty" contains: "Jpua, Princess Shang Xinchang, Song's wife entered the DPRK, and Emperor Xuanzong called her in-laws." At first, this title was only popular in the marriage of royalty, and Tang Xuanzong called his biological mother his biological mother, which shows the intimacy of his relationship.
Later, the title of in-laws spread to the people, and the people began to use this title, which has been used ever since.