The direction of these oscillations is the difference between longitudinal or transverse waves. In longitudinal waves, the vibrations are parallel to the direction of wave travel. In transverse waves, the vibrations are at right angles to the direction of wave travel.
Mechanical waves cause oscillations of particles in a solid, liquid or gas and must have a medium to travel through. Electromagnetic waves cause oscillations in electrical and magnetic fields.
Waves are described using the following terms: