What animal or part of animals were uesed to make glue?

Glue has traditionally been made from various animal parts, primarily collagen sourced from bones, hides, and connective tissues. Common animal-derived glues include those made from fish bladders (isinglass), hooves (Gelatin), and skin (hide glue). These materials are processed to extract collagen, which, when dissolved in water, forms a sticky adhesive. Today, while synthetic adhesives are more common, animal-based glues are still used in some applications, especially in woodworking and fine art restoration.