Cohesion, in physics, is the intermolecular attractive force acting between two adjacent portions of a substance, particularly of a solid or liquid. It is this force that holds a piece of matter together. Intermolecular forces act also between two dissimilar substances in contact, a phenomenon called adhesion. I am hoping that this answer has satisfied your query and it will be able to help you in your endeavor, and if you would like, feel free to ask another question.