Van der Waal interactions are nonspecific attractions created when one atom comes close enough to another one to disturb its electrons—inducing temporary dipoles that are cohesive.

Van der Waals and Geckos

Van der Waals interactions are so strong cumulatively that they can hold the weight of a gecko! This amazing feat is managed through the many interactions between the molecules on the tips of hairs on the gecko and molecules on the wall's surface. The surface area of the toe hairs is increased by having hundreds of thousands of hairs on each toe and having multiple projections from the tip of each hair, creating enough Van der Waals interactions to overcome gravity’s natural effect on a gecko, and allowing it to walk up a straight wall.

DNA

The structure of DNA is affected by weak, temporary noncovalent interactions. Van der Waals interactions between base pairs on neighboring “rungs” of the double helix hold the bases at an optimal angle to pack the double helix compactly.