Huygen's principle states that every point on a wavefront can be considered as a source of secondary spherical waves that spread out in all directions. These secondary waves then combine to form new wavefronts.
Related terms
Wavefront: A wavefront is an imaginary surface representing points in space where all particles of a wave are in phase (have identical positions within their respective cycles).
Diffraction refers to how waves bend or spread out when they encounter obstacles or pass through narrow openings.
Constructive interference: Constructive interference occurs when two or more waves combine to create larger amplitudes, resulting in increased intensity at certain points.