Oscillation

Oscillation is when something "vibrates", or repeats the same pattern. Many things in nature move back-and-forth or up-and down when pushed or struck. In time, natural oscillators slow down and stop because of friction.

 Examples 
The pendulum of a "grandfather clock", for example, is a very slow oscillator. 
The strings of pianos and string instruments "oscillate" when struck by a hammer. 
An ocean surface wave is the result of water moving up and down.
Circuits powered by electricity can "oscillate". Such circuits can be used to make sounds or radio waves.
Different chemicals, when you mix them together in the right order, can make some new things.  But then these things change back to the original ones, making this repeating pattern.  These are called chemical oscillators.

 Related pages 
Vibration

Category:Earthquake engineering
Category:Mechanics
Category:Oscillation