moiré pattern

A moiré pattern is the wavy, rippling visual effect that emerges when two regular patterns overlap at slight angles or different scales.

You see it when window screens overlap, when striped fabric folds over itself, or when photographing a television screen.

The interference creates new patterns that weren't in either original—sometimes shimmering, sometimes static.

Designers usually try to avoid moiré effects, though they're sometimes exploited for artistic or security purposes.