In mathematics, physics, and art, a moiré pattern (/mwɑːrˈeɪ/; French: [mwaˈʁe]) or moiré fringes are large scale interference patterns that can be produced when an opaque ruled pattern with transparent gaps is overlaid on another similar pattern. For the moiré interference pattern to appear, the two patterns are not completely identical, they must be displaced, rotated, etc. or have different, but similar pitch.
Moiré patterns appear in many different situations. In printing, the printed pattern of dots can negatively interfere with the image. In television and digital photography, a pattern on an object being photographed can interfere with the shape of the light sensors to generate unwanted artifacts. They are also sometimes created deliberately- in micrometers they are used to amplify the effects of very small movements.