Dietary fiber, also known as roughage or bulk, refers to the indigestible portion of plant foods that aids digestion and promotes overall health. It includes soluble fiber, which dissolves in water and helps regulate blood sugar and cholesterol levels, and insoluble fiber, which adds bulk to stools and facilitates bowel movements. A diet rich in fiber can prevent constipation, promote satiety, and reduce the risk of various chronic diseases like heart disease and diabetes.