Interleukin-23 (IL-23) is a heterodimeric cytokine composed of a p19 subunit and a p40 subunit. The p19 subunit is unique to IL-23, while the p40 subunit is shared with IL-12. IL-23 plays a crucial role in the immune system, particularly in the regulation of T cell responses. It is involved in the differentiation and maintenance of Th17 cells, a subset of T helper cells that produce pro-inflammatory cytokines such as IL-17 and IL-22. These Th17 cells are essential for host defense against extracellular pathogens but can also contribute to chronic inflammation and autoimmune diseases when dysregulated. IL-23 signaling occurs through the IL-23 receptor complex, which includes IL-23R and IL-12R尾1 subunits, and activates downstream pathways like JAK-STAT, leading to the production of various inflammatory mediators. Due to its involvement in immune-mediated inflammatory diseases, IL-23 has become a target for therapeutic interventions, with several biologics targeting the p19 subunit or the IL-23 receptor being developed and used in the treatment of conditions such as psoriasis, Crohn鈥檚 disease, and other autoimmune disorders.