The two major types of molecular forces are intermolecular and intramolecular. Intermolecular forces are forces that occur between multiple neighboring molecules. Hydrogen bonds in water are the perfect example. The oxygen atoms and hydrogen atoms from neighboring molecules share partial electrostatic interactions to form an extended network of additional stabilizing forces. This is what gives water such a high boiling point for such a small molecule.
Intramolecular forces are forces that act within a single molecule of a substance. These mostly consist of chemical bonds, both ionic and covalent in nature. These types of forces are much stronger than intermolecular forces because they represent full bonds as opposed to partial bonds.