Diffraction is the phenomenon of bending light waves around the edges of a barrier or opening. These phenomena can occur in almost every wave type. This occurrence is possible, according to the Huygens-Fresnel Principle and the principle of superposition of waves. The Huygens-Fresnel Principle states that every point on a wavefront is a wavelet's source. These wavelets scatter out in a forward direction equal to the speed of the originating wave.

Furthermore, the wavelets' tangent line is a new wavefront. At the same time, the concept of superposition states that the sum of incentives at any instant is the net outcome of numerous stimuli.