Since 1894 when humans began trying to treat breast cancer, treatment has made great progress, which is reflected in the continuous maturity of molecular classification; as well, the corresponding treatment strategies derived from molecular classification have constantly improved, including endocrine therapy for hormone receptor positive breast cancer, targeted treatment for patients with positive epidermal growth factor Her2, and chemotherapy for patients with triple‐negative breast cancer. The gene discussed is ERBB2; the disease is breast cancer.