The "Three Principles of the People" is a political philosophy developed by Sun Yat-sen, the founding father of modern China. These principles are Nationalism, Democracy, and the People's Livelihood. Nationalism emphasizes the importance of a unified nation free from foreign domination, while Democracy advocates for a government that represents the will of the people. The third principle, People's Livelihood, focuses on improving the economic well-being of citizens, ensuring that everyone has access to basic needs and opportunities. Together, these principles aimed to modernize China and promote social justice, laying the foundation for the country's political development in the early 20th century.