An example of a three-dimensional wave is sound. All waves have similar properties, therefore if we understand waves on strings or waves on water, then we can understand light waves. Waves transmit both energy and information through space from one point to another without transferring mass. The arrival of the wave provides information to an observer on the distant shore that something happened to cause the wave. In this case, the stone falling into the water is the source of both the wave and the energy transmitted by the wave.
Waves exist only when there is motion.
Since motion cannot be illustrated easily on paper, we will illustrate the shape of a wave at a particular instant in time. Since light waves are transverse, we will only consider transverse waves. The velocity of a wave is the product its wavelength and frequency. We will consider the vector properties of waves when discussing polarization. A ripple or pulse is a piece of a wave, and pulses are easier than waves to illustrate.