What is "moire pattern"

n. an optical effect formed when one family of curves is superposed on another, the lines of the overlapping figures crossing at an ange less than about 45°; the moiré lines are then the locus of the points of intersection

In mathematics, physics, and art, a moiré pattern (; French: ) or moiré fringes is a secondary and visually evident superimposed pattern created, for example, when two identical (usually transparent) patterns on a flat or curved surface (such as closely spaced straight lines drawn radiating from a point or taking the form of a grid) are overlaid while displaced or rotated a small amount from one another.

In physics, its manifestation is the beat phenomenon that occurs in many wave interference conditions.