The foundational duty of diplomacy is the management of inter-state relations and relations between states and other international players. Public diplomacy is magnifying of national interests by giving information, engagement and putting influence on people all around the world. Public diplomacy is a change in diplomacy resulted from the effect of globalization on power. Public diplomacy is recently entered into political terms. Due to the position of the Islamic Republic of Iran in the current world, the importance of this concept for our country is doubled. Therefore, exploring its dimensions and characteristics in western literature is of great significance. This article aims to elaborate the most important definitions of public diplomacy and its dimensions and alternatives