John Stuart Mill shapes the social and moral ideals of the modern world like few others. Works such as "On Liberty," "Utilitarianism," and "System of Logic" are among the most discussed classics of the philosophical tradition. His "Subjection of Women" is a foundational work of modern feminism, and in "Considerations on Representative Government" and other writings, he develops a theory of deliberative democracy. This introduction provides an overview of the essential insights and concerns of John Stuart Mill and explains the central research controversies. It places particular emphasis on illustrating the connections between Mill's ideas, which are often treated separately, in political economy and theoretical and practical philosophy. In doing so, Mill emerges as an astonishingly relevant and radical thinker.