Sun Yat-sen was a Chinese revolutionary who played a key role in the overthrow of the Qing dynasty. He served as the first provisional president of the Republic of China in 1912. Throughout his life, Sun struggled to establish a modern democratic republic in China through revolutionary activities and exile, developing the political philosophy of the Three Principles of the People. He remains a revered figure in both China and Taiwan for his role in transforming China from an empire to a republic and promoting nationalism, democracy, and people's livelihood.