The article by Barry Halliwell provides an overview of the field of redox biology, emphasizing the balance between antioxidants and free radicals in aerobic life. Free radicals are not inherently harmful, and antioxidants serve to control their levels to prevent excessive damage. The evolution of aerobic life is discussed, highlighting the role of oxygen in energy production and the development of antioxidant defenses. The article also delves into the mechanisms of oxygen toxicity, the formation of reactive oxygen species (ROS), and the importance of antioxidant defenses in maintaining cellular viability. It explains how ROS can be beneficial in certain contexts, such as defense against microorganisms and signaling, but can also cause oxidative stress and damage when their production exceeds the body's ability to repair it. The article concludes by discussing the complex interplay between ROS and antioxidants, and how this balance is crucial for health and longevity.The article by Barry Halliwell provides an overview of the field of redox biology, emphasizing the balance between antioxidants and free radicals in aerobic life. Free radicals are not inherently harmful, and antioxidants serve to control their levels to prevent excessive damage. The evolution of aerobic life is discussed, highlighting the role of oxygen in energy production and the development of antioxidant defenses. The article also delves into the mechanisms of oxygen toxicity, the formation of reactive oxygen species (ROS), and the importance of antioxidant defenses in maintaining cellular viability. It explains how ROS can be beneficial in certain contexts, such as defense against microorganisms and signaling, but can also cause oxidative stress and damage when their production exceeds the body's ability to repair it. The article concludes by discussing the complex interplay between ROS and antioxidants, and how this balance is crucial for health and longevity.