There are many types of glue.

Glue is a sticky material (usually a liquid) that can stick two or more things together. Glue can be made from plant or animal parts, or it can be made from oil-based chemicals.

The first glues may have been natural liquids that come out of trees when they are cut. Later, people learned to make glue by boiling animal feet, cartilage or bones. Some very strong glues were first made from fish bones, rubber or milk.