Wall clock or quartz clock work on a principle called piezoelectricity. Piezoelectricity is the electric charge that gathers in certain solid materials. Some crystals have electrical properties therefore if you condense them, they emit a charge. On the other hand, if you convey an electrical charge via them they vibrate. You can read more at http://www.ehow.com/how-does_5607621_quartz-clocks-work.html.
I'm not sure what you mean by "principles". The principle of all clocks is the same: they count little time segments continuously, and then show you how many they counted. This can be done mechanically or electronically, but the principle is the same.