What do intermolecular forces have to do with polar and/or non-polar molecules?

There are three main types of intermolecular forces. London Dispersion, dipole-dipole, hydrogen bonding. All molecules exhibit London dispersion forces. Polar molecules exhibit both LDF and dipole-dipole because of the differences on electronegativity. If hydrogen is bonded with one of the very electronegative molecules (N, O, or F), it has hydrogen bonding and is usually polar (Ex. Water).