How is vibrations made on a guitar?

The strings vibrate by either using a bow (with a friction agent called Rosin on it ) or by pizzicato (plucking the strings with a finger). This vibration passes through the bridge and is then amplified by the belly and the back of the instrument via a sound post (viewed inside by looking through the "F" holes in the belly). The tone and volume are greatly affected by the quality of the wood and 'set-up' of the strings and bridge.