Dietary fiber is not a single chemical compound but a category of indigestible plant polysaccharides, primarily cellulose, hemicelluloses, pectins, and lignins. Cellulose, the main component, consists of linear chains of beta-1,4-linked D-glucose units forming strong hydrogen-bonded microfibrils. It adds bulk to food, aids digestion, regulates blood sugar, and lowers cholesterol. As a food compound, it is insoluble in digestive fluids and passes through the gut largely unchanged, promoting gut health via fermentation by microbiota. Fiber content varies in foods like grains, vegetables, and fruits. No specific boiling or melting point applies due to polymeric nature and decomposition before melting.