Hello. There are many types of waves, but they all have similar properties. All Waves propagate through a material, or medium, and are created by some initial displacement in this material (ie, a rock thrown into water). The energy from this initial displacement causes the material nearby to also displace, which in turn displaces material near it... which creates a wave of energy propagating outwards. It is important to note that the material may move around as the wave passes, but it is the energy which is propagating outwards, not the material itself.