Adhesion is the process in which dissimilar particles stick together. In the case of similar particles, this effect is called cohesion. Adhesion results from the physical properties of the interface between two phases. The forces that result in adhesion are not fully known, there are different explanations. Five different types of adhesion have been proposed:

• Mechanical adhesion: Adhesive materials fill the voids or pores, and interlock
• Chemical adhesion: Where they join, two materials form a Chemical compound.
• Dispersive adhesion: Two materials are held together by Van der Waals forces
• Electrostatic adhesion: Two materials are held together by electrostatic charge
• Diffusive adhesion: Two materials are held together with Atomic diffusion, it is derived from a sanskrit word adhere meaning to hold on