The future location of a wave front can be determined by considering each point on the present wave front as a source for new wavelets. The new, future wave front is the envelope of these wavelets. This is Huygens' Principle. If a barrier blocks parts of the wave some of the wavelets will be stopped. This will cause the envelope of the remaining wavelets to bend past the edges of the barrier; the wave bends past the edges of the hole. This behavior is known as diffraction and is characteristic of waves-of all waves. As the hole becomes smaller this bending or diffraction becomes greater.