Adhesion
![Dew drops adhering to a spider web](/Images/godic/202501/11/Spider_web_Luc_Viatour0604.jpg")
![Adhesion of a frog on a wet vertical glass surface.](/Images/godic/202501/11/-Sticking-under-Wet-Conditions-The-Remarkable-Attachment-Abilities-of-the-Torrent-Frog-Staurois-pone.0073810.s004.ogv0604.jpg")
![Diagram of various cases of cleavage, with each unique species labeled. A: γ = (1/2)W11
B: W12 = γ1 + γ2 – γ12
C: γ12 = (1/2)W121 = (1/2)W212
D: W12 + W33 – W13 – W23 = W132.](/Images/godic/202501/11/Lease0440604.jpg")
![Cohesion causes water to form drops, surface tension causes them to be nearly spherical, and adhesion keeps the drops in place.](/Images/godic/202501/11/Drops_I0604.jpg")
IUPAC definition
Process of attachment of a substance to the surface of another substance.
Note 1: Adhesion requires energy that can come from chemical and/or physical
linkages, the latter being reversible when enough energy is applied.
Note 2: In biology, adhesion reflects the behavior of cells shortly after contact
to the surface.