Soft power is a term in international relations that refers to a state's ability to influence the behavior of other states through attraction and persuasion, rather than through coercion or military force. It is based on a state's cultural, ideological, and institutional appeal, as well as its ability to shape the preferences and attitudes of others through diplomacy, international institutions, and cultural exchange.
Source: Nye, J. S. (1990). Soft power. Foreign Policy, 80, 153-171.