Propaganda is a technique of persuasion aimed at influencing public opinion towards some cause or position. It involves the selective presentation of facts for ideological or commercial purposes. Modern propaganda dates from the World War One period and shares some characteristics with advertising and public relations. Often labelled as ‘crude’ or ‘manipulative’, it is in fact a powerful tool for controlling opinion which relies on a sophisticated mastery of the way popular attitudes and perceptions are formed. Totalitarian regimes have used propaganda in different ways and have usually been careful not to undermine its efficacy by excess. Indeed, some of the most effective propaganda is subtle rather than overt and may deploy visual images and material culture.