All the particles in the forward wave medium gain periodic motion. The spread of each particle is equal but they do not spread evenly at a given time. The vibration of one particle in the direction of the wave is transferred to the next particle , so that the wave travels through the medium at a certain speed. The phase of medium particles is carried from one particle to another. The particles in the medium are never stable. In the case of moving transverse waves, the wavelength consists of one wavelength and one wavelength, and in the case of running longitudinal waves, the wavelength consists of one contraction and one extension. All particles gain periodic motion except the fixed points of the stationary wave medium. The periodicity of the particles is the same but the dispersion is not the same. The waves are stationary in the medium, and their contraction and propagation in some places at equal distances are visible once and invisible again. Besides, all the particles between two motionless points are in the same state but the spread is the same. With each full vibration the particles come to a stationary state twice. The wavelength of a fixed wave is the distance between three successive pulsed points or three pulsed points.