β-Nicotinamide adenine dinucleotide (NAD) is widely used in biochemical research as a coenzyme in redox reactions, playing a critical role in metabolic processes such as glycolysis, the citric acid cycle, and oxidative phosphorylation. It is essential for energy production in cells, facilitating the transfer of electrons during these reactions. In cellular biology, NAD is utilized to study enzyme kinetics, metabolic pathways, and cellular respiration. It also serves as a substrate for enzymes like sirtuins and PARPs, which are involved in DNA repair, gene expression, and aging processes. Additionally, NAD is employed in diagnostic assays to measure enzyme activity and in pharmaceutical research to explore its potential in treating metabolic disorders, neurodegenerative diseases, and age-related conditions. Its applications extend to biotechnology, where it is used in the production of biofuels and other bioproducts.