Vibration is the repeated movement of an object around its mean position as a result of the application of an external force. Such motion can be linear, circular, periodic or non-periodic.
When an external force is applied, the atoms constituting the object get displaced from their mean position. With the release of the force, they return to their mean position but then travel beyond it due to the momentum they have gained during the motion. This cycle repeats until it is exhausted by friction and the atoms come to a halt at their mean position.
Vibration is a form of oscillation. However, in contrast to oscillation, which occurs in all types of systems, including mechanical, electrical, biological, and even societal, vibration is associated only with mechanical systems that have mass and elasticity.
Vibration plays a fundamental role in music, because it is what enables musical instruments to produce their sound. The sound is initiated by creating vibrations through some act, according to the type of instrument, such as plucking or hitting or rubbing a bow against a string, passing air over or through a tube or hole, or hitting a stretched membrane. These vibrations are transmitted to a specially shaped hollow wooden structure, metal tube, etc. which greatly amplifies them, thereby creating the musical sound. Loudspeakers operate by using an electromagnet to force an elastic diaphragm to vibrate.