"Capital in the Twenty-First Century" is a book by Thomas Piketty that explores the dynamics of wealth and income inequality in modern economies. Piketty analyzes historical data to show how wealth concentration has evolved over time, particularly since the 1970s, and argues that the rate of return on capital often exceeds economic growth, leading to greater inequality. The book emphasizes the importance of policy interventions to address these disparities, such as progressive taxation and wealth redistribution. Piketty's work has sparked widespread discussion about economic systems and the role of government in managing inequality in the global economy.