Glues are part of a larger family called adhesives. The two classes are distinguished by the fact that glue comes from organic compounds while adhesives are chemical-based. Adhering materials called epoxies, caulks, or sealants are also chemical compounds that have special additives to give them properties suitable for particular jobs or applications.

Glue came into being when ancient tribes discovered that the bones, hides, skin, sinew, and other connective tissues from animals could be processed to remove collagen, the protein in these tissues. The collagen was sticky and was useful for holding things together. Milk solids, known as casein, and blood albumin can also be used as a basis for glue. Dried serum from cows' blood yields albumin that coagulates (clumps together) when it is heated and becomes insoluble in water.