On Liberty by John Stuart Mill is a seminal work advocating for individual freedom and limited government intervention. Mill argues that people should be free to act as they wish, as long as their actions do not harm others. He emphasizes the importance of free speech, individuality, and the need to protect minority opinions from the "tyranny of the majority." The essay introduces the "harm principle," which justifies intervention only to prevent harm to others, and remains a crucial text in discussions on liberty and human rights.