Van der Waals forces are weak attractions that occur between molecules or parts of molecules. They arise from temporary shifts in electron density, which create small, localized charges. These forces play a crucial role in various physical properties, such as boiling and melting points, and are significant in the behavior of gases and liquids. There are three main types of Van der Waals forces: dipole-dipole interactions, induced dipole interactions, and London dispersion forces. Although they are weaker than covalent or ionic bonds, Van der Waals forces are essential for the stability and structure of many biological molecules, including proteins and DNA.