

Transverse waves
Transverse waves the displacement of the medium is perpendicular to the direction of propagation of the wave. A ripple on a pond and a wave on a string are easily visualized transverse waves.
video: http://www.youtube.com/watch?v=UHcse1jJAto

Longitudinal Waves
In longitudinal waves the displacement of the medium is parallel to the propagation of the wave. A wave in a "slinky" is a good visualization. Sound waves in air are longitudinal waves.
Video: http://www.youtube.com/watch?v=aguCWnbRETU
Sound Waves in Air
A single-frequency sound wave traveling through air will cause a sinusoidal pressure variation in the air. The air motion which accompanies the passage of the sound wave will be back and forth in the direction of the propagation of the sound, a characteristic of longitudinal waves.
video: http://www.youtube.com/watch?v=dhbS_1MdLq8
More video: http://www.gcse.com/waves/waves2.htm
Amirul Haziq[22]