Van de Waals forces, from the name of the Dutchman Johannes Diderik Van der Walls, (1837 -1923), Nobel prize winner for physics in 1910, are weak residual electromagnetic forces of quantum origin exerted between molecules and even between neutral atoms.
They were initially introduced in the form of phenomenological terms in the Van der Waals equation of state for so-called real gases which do not behave according to the ideal gas law.
It was not until Schrödinger introduced his equation that these forces, which no longer vary as 1/R2, as for electrostatics, but as 1/R7, could be modelled more accurately.
The forces are actually a combination of essentially three distinct types of force resulting from different effects:
Geckos climb walls largely through the existence of Van de Waals forces.