Final answer:
London dispersion forces result from temporary fluctuations in electron distribution within atoms and molecules, causing momentary dipole moments and very weak intermolecular attractions.
Step-by-step explanation:
London forces, also known as London dispersion forces, are very weak intermolecular interactions that can occur in all molecules, including polar and nonpolar ones. These forces are due to the momentary changes in electron distribution within an atom or molecule, leading to temporary dipole moments.
Consequently, when one molecule has a fleeting dipole, it can induce a dipole in an adjacent molecule, leading to an attraction between these temporary dipoles. Although these London forces are transient and weaken rapidly with increasing distance, they are significant as they can influence the physical properties of substances.