Intermolecular forces are forces that holds a molecule together.
Molecular compounds are able to display a wide range of physical properties due to the different intermolecular forces.
London Dispersion Forces - Weak forces which holds molecules together in solid, liquid and gas. These are cause by the temperary dipole movements of the molecule.
Dipole-dipole Forces - Occurs when the opposite ends of the molecule are attracted to each other. They are slightly stronger in comparison to London Dispersion Forces.
Hydrogen Bonding - Occurs when hydrogen is bonded to a highly electromagnetive atom (etc.N,O,F).