Glycerin is used as a humectant, solvent, sweetener, and preservative across various industries, most notably in cosmetics, pharmaceuticals, and food. In skincare and toiletries, it moisturizes and softens skin; in medications, it's in cough syrups, lozenges, and eye treatments; and in food, it sweetens, thickens, and prevents products like cakes and ice cream from drying out.