A 'revolution' usually refers to an overthrow of a government or disruption of social order to make way for a new system. "The French revolution redefined political power throughout the country." In Marxism 'revolution' refers to the class struggle which is expected to lead to political change. Outside of political contexts, 'a revolution' can refer to a dramatic change in the way something is approached or done. "The use of electricity lead to a revolution in farming and manual labour." When we are talking about things that are revolving, such as a door, the planets, something mechanical or revolving responsibilities a 'revolution' refers to one complete orbit or circular movement from beginning to end. "It takes one year for the Earth to make a complete revolution around the Sun."