On Liberty is a landmark work of political philosophy that explores the importance of individual freedom in society. In this influential book, John Stuart Mill argues that every person should have the right to think, speak, and live freely, as long as their actions do not harm others. The book strongly defends freedom of speech and expression, emphasizing that open discussion and differing opinions are necessary for the discovery of truth and the progress of society. Mill also warns against the "tyranny of the majority," where social pressure and public opinion can limit individuality and personal development.