A diffraction pattern is a series of light and dark bands created when waves, such as light or sound, encounter an obstacle or pass through a narrow opening. This phenomenon occurs because waves spread out after interacting with the edges of the obstacle or aperture, leading to constructive and destructive interference. In optics, diffraction patterns are often observed in experiments involving lasers or slits. The resulting pattern can provide valuable information about the wavelength of the waves and the size of the opening or obstacle, making it a useful tool in fields like physics and engineering.