3 Types of wave
A wave may be defined as a periodic, or regularly repeating, disturbance that transports energy from one place to another.
For example, a stone dropped into the centre of a pond generates a wave on the surface of the water. The wave travels outwards and the energy it transports would eventually cause a cork at the edge of the pond to bob up and down with a regular motion.
Other sorts of wave also exist. It was one of the greatest physicists of the 19th century, James Clerk Maxwell (1831–1879), who established that light is an electromagnetic wave. In fact, light sometimes behaves like a wave and sometimes as a stream of particles.
There are two main wave types, distinguished by the direction of the motion of the particles of which they are made.