A Moire pattern is a large-scale interference pattern that can be produced when a partially opaque ruled pattern with transparent gaps is overlaid on another similar pattern. The patterns must not be completely identical, but rather displaced, rotated, or have slightly different pitch for the Moire interference pattern to appear. Moire patterns appear in many situations, such as in printing, television, digital photography, and micrometers. They can be created deliberately to amplify the effects of very small movements.