Nitric oxide synthases (NOS) are a group of enzymes responsible for producing nitric oxide (NO), a crucial signaling molecule in the body. There are three main types of NOS: neuronal NOS (nNOS), endothelial NOS (eNOS), and inducible NOS (iNOS). Each type is found in different tissues and plays distinct roles in regulating various physiological processes, such as blood flow, neurotransmission, and immune responses. Nitric oxide acts as a vasodilator, helping to relax blood vessels and improve circulation. It also plays a role in the immune system by helping to fight off pathogens. Dysregulation of NOS can lead to various health issues, including cardiovascular diseases and inflammatory disorders.