A wave is a disturbance which always moves forward from the source. A wave can be of two types:
1. Mechanical waves: These waves can transport energy through matter only without actually moving the matter along. Example: Sound wave
2. Electromagnetic waves: The waves can transport energy through space.
Example: Radio waves
Another types of waves are:
1. Longitudinal waves: The waves transfer energy parallel to the motion of the wave. The particles of the medium oscillate along the direction of motion of wave.
2. Transverse waves: The waves transfer energy perpendicular to the motion of the wave. The particles of the medium oscillate perpendicular to the direction of motion of wave.