van der Waals Forces
Definition
The weak, universal attractions between all molecules: even noble gases feel them. They are the reason gases can be liquefied.
Technical definition
van der Waals forces are weak intermolecular attractions present between all atoms and molecules, including dipole-dipole, dipole-induced dipole, and London dispersion forces. Individually weak (0.1-10 kJ/mol) but collectively significant, they govern condensation and many material properties.
Example
Geckos stick to walls because millions of tiny foot hairs create enough van der Waals attraction to support the animal's weight.
Common confusion
van der Waals forces are an umbrella term that INCLUDES London dispersion forces. Dispersion forces are one type of van der Waals force, not something separate.