# Translations:Diffraction/7/en

In the general sense, both *interference* and *diffraction* refer to effects resulting from the superposition of two or more waves at a given point in space. There is no essential mathematical difference between interference and diffraction. However, in more restricted usage, *interference* is used to describe effects that result from the superposition of two or more wave trains (as in the case of water-layer reverberations of seismic waves), and *diffraction* is used to describe interference effects caused by the presence of an aperture or an obstacle in the path of a wave (as in the bending of seismic waves around obstacles). In modern usage, the terms *interference* and *diffraction* still refer more or less to the types of problems studied by Hooke and Grimaldi, respectively.