Define Intermolecular forces

Inter molecular forces are the forces which mediate interaction between molecules, including forces of attraction or repulsion which act between molecules and other types of neighboring particles, e. g., atoms or ions. Some include Hydrogen bonds and and Metallic bonding.

Intermolecular forces are the forces that happen between molecules. Just like an interstate is a highway that goes between different states, intermolecular forces are forces are forces between different molecules.

Hydrogen bonds are the strongest of the intermolecular forces.