立冬是中国二十四节气中的一个重要节气，表示农历的第18个节气，一般在每年的11月7日或8日。在中国传统文化中，立冬是一个重要的节日，人们会在这一天吃饺子来庆祝。

据传说，吃饺子是始于南北朝时期的一位名叫张仲景的医生。在当时的北方地区，立冬时节气渐寒，人们容易感冒和患上其他疾病。为了帮助人们抵御寒冷和预防疾病，张仲景想出了一个办法：他将药材和一些新鲜的蔬菜一起包在面皮里，制成了一种能够加强人体免疫力的食物——饺子。

随着时间的推移，饺子逐渐成为中国传统文化中的一种重要饮食文化。在立冬这一天，人们会聚在一起包饺子，共同庆祝这一节日。在包饺子的过程中，家人和朋友之间的互动和交流也增强了人们的感情。

总之，立冬吃饺子的习俗源远流长，已经成为了中国传统文化中的一个重要组成部分，代表着人们对健康、美好生活的向往和追求。

Translation:

Lidong, one of the 24 solar terms in China, falls on November 7th or 8th each year, marking the beginning of winter. In Chinese culture, Lidong is an important festival, and people celebrate it by eating dumplings.

According to legend, the tradition of eating dumplings on Lidong originated from Zhang Zhongjing, a famous doctor during the Northern and Southern Dynasties. In the cold weather of early winter, people were prone to catching colds and other illnesses. To help them resist the cold and prevent illnesses, Zhang Zhongjing invented a food that combined herbs and fresh vegetables wrapped in dough - dumplings.

Over time, dumplings became an important part of Chinese food culture. On Lidong, people gather together to make dumplings and celebrate the festival. During the process of making dumplings, family and friends interact and bond with each other.

In summary, the tradition of eating dumplings on Lidong has a long history and has become an important part of Chinese culture, representing people's pursuit of health and a better life.