Dietary fiber is the part of food from plants that cannot be digested. Dietary fiber helps to absorb water or remove waste from the body. Dietary fiber has many parts that plants have, and is eaten in plant foods.
Dietary fiber includes substances like cellulose, wax and lignin, among others. The term "fiber" is not the best way to describe it, because many of these substances are not actually fibers.
Dietary Fiber  is grouped if it is soluble or insoluble. Soluble means if it helps to absorb water or not. If it is insoluble, it helps remove wastes from the body.
Foods rich in fibers: fruits, vegetables and grains.
American Fiber Intake Gap