Hydrogen bonding is the strongest form of intermolecular force but only works in certain molecules where the electronegativity is very large. The bond between a hydrogen atom and nitrogen, oxygen or fluorine has a large electronegativity, as a result the dipole that is created is large. This means that the intermolecular force between these molecules is the strongest intermolecular force. For example in water there is a hydrogen bonded to an oxygen. Hydrogen has an electronegativity of 2.2 and oxygen has an electronegativity of 3.44. This electronegativity difference is 1.24, this is not great enough to mean it is ionically bonded on the bonding continuum but the dipole is so large that the intermolecular force is very strong.
Intermolecular forces are temporary interactions between ions, atoms or compounds that are not considered to be sharing electrons.
Electronegativity is the ability of an atom to attract electrons in its bond determined by the nuclear charge, number of protons and the number of shells.