London dispersion forces are weak intermolecular attractions that occur between all atoms and molecules. They arise from temporary fluctuations in electron distribution, which create momentary dipoles. These dipoles can induce similar dipoles in neighboring particles, leading to a brief attraction. Although London dispersion forces are the weakest type of intermolecular force, they become significant in larger atoms or molecules with more electrons. As the size and number of electrons increase, the strength of these forces also increases, influencing properties like boiling and melting points in substances such as noble gases and hydrocarbons.