The string quartet is, together with the symphony for orchestra and the piano sonata, one of the main instrumental genres that have been vertebrate the history of western music in the last three centuries. This great compositional tradition has gone from Mozart, Boccherini, Beethoven and Schubert to Webern, Bartók, Shostakovich and, in the last decades, Elliott Carter. The contribution of Joseph Haydn to the gestation of the quartet was so transcendental that at times he has been considered as his "inventor". Conceived as an introduction to the quartettic legacy of this fundamental Austrian composer, this book reveals the novelties, audacies and innovations that explain the greatness of these works, while inserting them in the historical and aesthetic context in which they were composed. Aspire to become an indispensable guide for fans and scholars interested in knowing this extraordinary music, providing some keys to facilitate their understanding and enjoyment.