Equity is a means by which English law ensures fair outcomes in individual cases where the strict application of the common law or statute would otherwise generate injustice. The core principles of English equity are in sympathy with Aristotle’s philosophical ideas. In 1873, the Judicature Act provided that the courts of common law and those of equity should be merged so that any single court could rule on any question, no matter whether it related to principles of equity or to rules of common law. A court of equity is therefore making an order, based on the facts of an individual case, to prevent that particular person from continuing to act unconscionably. The study of equity is concerned with the isolation of the principles upon which judges in particular cases seek to exercise their discretion. The chapter also presents an overview on the key concepts discussed in this book.