Gravimetric analysis in simple terms is analysis by weight. In volumetric analysis( which we refer as titrations) volume is measured, from which we calculate the strength of solution. For example, determining  amount of chlorine in the given sample of water, first we will have to precipitate it with silvernitrate to get silver chloride, filter , wash , dry and finally weigh it.

For details refer to http:// www.newi.ac.uk/buckleyc/gravi.htm