Dietary fiber, an important nutrient found in plant-based foods, possesses various health benefits. This chapter provides a brief overview of the recommended and actual intake of dietary fiber, the physiological properties and effects on human metabolism and physiology, and the epidemiological and experimental evidence on the association between fiber and health parameters. Previous literature has shown the potential benefits of dietary fiber in lowering blood glucose and lipid levels and improving bowel movements. Numerous studies have also shown the association between higher dietary fiber intake and a lower risk of various chronic diseases, including diabetes mellitus, dyslipidemia, chronic kidney disease, cardiovascular disease, cancer, and all-cause mortality. This chapter also briefly discusses the role of dietary fiber as carbohydrate quality, its relevance to environmental epidemiology, and recommendations for clinical practice, research, and health policy.