Utilitarianism by John Stuart Mill is a scminal work in ethical philosophy that explores the principles of utilitarianism-a consequentialist ethical theory that assesses actions based on their ability to maximize overall happiness or pleasure. Published in 1861, Utilitarianism builds upon the ideas of Jeremy Bentham, but Mill adds nuances to the theory, emphasizing the qualitative aspects of pleasure and introducing the concept of higher and lower pleasures. In this foundational text, Mill argues that actions are right in proportion as they tend to promote happiness and wrong as they tend to produce the reverse of happiness. Mill's eloquent defence of utilitarianism addresses objections, refines the theory, and underscores the importance of individual rights within the framework of utility. ""Utilitarianism"" remains a cornerstone in moral philosophy, offering insights into the ethical calculus that continues to shape debates on morality and public policy. With clarity and rigour, Mill's work remains a fundamental reference for those interested in the foundations of ethical reasoning.