Esperanto, spoken by thousands of people across the world, is the most successful international language project. In this book, the French linguist and literary critic Pierre Janton describes the history of Esperanto since its invention in nineteenth-century Eastern Europe and offers a comprehensive linguistic description of the language. This book is the best general introduction to Esperanto and its role in the modern world. Rooted in the populism and internationalism of the late nineteenth century, Esperanto owes its origins in part to western European educational currents and in part to the cultural history of eastern European Jewry. It is a fascinating historical and sociological phenomenon as well as a remarkable linguistic system. The book contains a survey of today's movement for the promotion of Esperanto as an international language, and a description of the extensive literature in Esperanto, both original and translated. Janton also provides a survey of the other global language projects, explaining why Esperanto has prevailed.