Antioxidants are among the most studied topics both in the area of food science and nutrition. Antioxidants were firstly used as just a food preservative, then it was realized that they inhibited the oxidation processes not only in foods but also in human metabolism. Then, they gained the spotlight with their important roles both in foods and in human body. Consequently, significant number of research articles focusing on the antioxidant content of different foods, analytical methods for better estimation and measurement of the antioxidant capacity of foods have been publishing for years. In addition, there is a growing interest among the food scientists in improving the knowledge on the physiological effects of antioxidants in the human body. This review provides a historical overview about antioxidants covering their occurrence and roles in various foods, analytical methods for the determination of their antioxidant capacity, and their physiological effects.