StellarWaves
A wave is a disturbance in a medium that transfers energy without changing the net position of the particles in that medium. Mechanical waves such as sound or ocean waves propagate through a physical medium such as air or water. Light waves are a special case because they are actually electromagnetic waves which do not need a medium to propagate through. Electromagnetic waves will always move at a constant velocity within a vacuum. For example, light is an electromagnetic wave.
The crest of the wave is the highest point of the wave while the trough is the lowest point. The amplitude is the height of the wave measured from its rest position. The amplitude of a wave is directly correlated to how much energy the wave will carry or how loud a sound wave will feel. Wavelength is the distance between two of the same repeating parts of the wave. All waves can be modeled as a sine or cosine curve (or the sum of many such waves).