The Shang Han Lun, or "Treatise on Cold Damage," is a classical Chinese medical text attributed to the physician Zhang Zhongjing from the Han dynasty. It focuses on diagnosing and treating diseases caused by cold and external pathogens. The text is foundational in traditional Chinese medicine, emphasizing the importance of understanding the body's responses to environmental factors. The Shang Han Lun is structured into several sections, detailing various syndromes and their corresponding treatments. It introduces concepts such as yin and yang, as well as the balance of the body's energies. This work has influenced countless practitioners and remains a key reference in the study of traditional Chinese medicine.