Interference is the phenomenon of two or more waves overlapping and interacting with each other. There are two main types of interference: constructive and destructive. Constructive interference occurs when two waves combine to create a larger amplitude, resulting in a wave with a higher intensity. Destructive interference occurs when two waves combine to create a smaller amplitude, resulting in a wave with a lower intensity. In both cases, the waves are still present and continue to propagate, but the resulting waveform is modified by the interference.