Adhesion is the act of sticking together, and is a term used in many different fields. In biology, ADHESION is the process by which cells stick to each other or to surfaces. In physics, ADHESION is the force that causes two surfaces to stick together. In chemistry, ADHESION is the attraction between molecules of different substances. ADHESION is also used in engineering, where it refers to the bonding of two materials. In everyday life, ADHESION is the process of sticking two objects together with glue, tape, or other adhesive materials.