In the VD/VDR system, VD refers to vitamin D, and VDR stands for the vitamin D receptor, which belongs to the nuclear receptor family. VDR contains DNA binding domains and ligand binding domains, primarily localizing in the cell nucleus to regulate vitamin D-dependent gene expression. VDR is involved in regulating calcium and phosphate metabolism, cell proliferation, differentiation, and immune function by influencing various signaling pathways such as Wnt/β-catenin and NF-κB. VDR shows specific expression in various cells and tissues and is closely associated with processes such as skeletal health, immune regulation, and cancer suppression. Mutations or changes in VDR gene expression can lead to conditions such as osteoporosis, rickets, and immune dysfunction.