Constructive interference occurs when two or more waves meet and combine to form a wave of greater amplitude. This phenomenon happens when the peaks of the waves align, reinforcing each other. For example, if two sound waves of the same frequency and phase overlap, they produce a louder sound than either wave alone. In practical applications, constructive interference is crucial in various fields, such as acoustics and optics. It is responsible for the bright spots seen in patterns created by light waves passing through slits, as described by Thomas Young's double-slit experiment. Understanding this concept helps in designing better audio systems and optical devices.