London dispersion forces (LDF) are a type of intermolecular force acting between atoms and molecules that are normally electrically symmetric; that is, the electrons are symmetrically distributed with respect to the nucleus. These forces arise due to temporary fluctuations in the electron distribution within molecules, creating temporary dipoles.
In any given moment, electrons might be distributed unevenly within a molecule, resulting in a temporary dipole moment. These temporary dipoles induce corresponding temporary dipoles in neighboring molecules. These induced dipoles then attract each other, creating a weak electrostatic force.