Oxidative stress, caused by an imbalance between reactive oxygen species (ROS) and reactive nitrogen species (RNS), is a key factor in the development of chronic diseases and aging. ROS and RNS, including superoxide radicals, hydrogen peroxide, hydroxyl radicals, and nitric oxide, are involved in various physiological processes but can cause damage to DNA, proteins, and lipids when present in excess. Oxidative stress is linked to conditions such as cancer, cardiovascular disease, diabetes, and neurodegenerative disorders. Antioxidants, including enzymes like superoxide dismutase (SOD), catalase, and glutathione peroxidase, as well as small molecules like vitamins C and E, play a crucial role in neutralizing ROS and mitigating oxidative damage. Antioxidant enzymes and small molecules work together to maintain redox balance and prevent cellular damage. Additionally, certain antioxidants, such as flavonoids, may have prooxidant properties that enhance cellular antioxidant defenses. Redox metal-based enzyme mimetics and sirtuins are promising therapeutic targets for age-related diseases. The balance between ROS and antioxidants is essential for maintaining health and preventing disease.Oxidative stress, caused by an imbalance between reactive oxygen species (ROS) and reactive nitrogen species (RNS), is a key factor in the development of chronic diseases and aging. ROS and RNS, including superoxide radicals, hydrogen peroxide, hydroxyl radicals, and nitric oxide, are involved in various physiological processes but can cause damage to DNA, proteins, and lipids when present in excess. Oxidative stress is linked to conditions such as cancer, cardiovascular disease, diabetes, and neurodegenerative disorders. Antioxidants, including enzymes like superoxide dismutase (SOD), catalase, and glutathione peroxidase, as well as small molecules like vitamins C and E, play a crucial role in neutralizing ROS and mitigating oxidative damage. Antioxidant enzymes and small molecules work together to maintain redox balance and prevent cellular damage. Additionally, certain antioxidants, such as flavonoids, may have prooxidant properties that enhance cellular antioxidant defenses. Redox metal-based enzyme mimetics and sirtuins are promising therapeutic targets for age-related diseases. The balance between ROS and antioxidants is essential for maintaining health and preventing disease.