An adhesive is any substance applied to the surfaces of materials that binds them together and resists separation. The use of adhesives offers many advantages over binding techniques such as sewing, mechanical fastening, thermal bonding, etc. These include

- the ability to bind different materials together,

- to distribute stress more efficiently across the joint,

- the cost effectiveness of an easily mechanized process,

- an improvement in aesthetic design,

- and increased design flexibility.

Adhesives are typically organized by the method of adhesion. These are then organized into reactive and non-reactive adhesives, which refers to whether the adhesive chemically reacts in order to harden.。