The Sonata - literally 'soundpiece' - is possibly the most fundamental of all genres of 'pure' instrumental music; certainly it is the most long-lived, first appearing around 1600 and being used - with various connotations - until today. The present book does not and cannot present history of the sonata as a unified genre (such as, for example, the string quartet) – there is too little that a Gabrieli ensemble sonata has in common with a Beethoven piano sonata or a Corelli trio sonata with the works by Pierre Boulez. The common trait that they do share is that they are 'pure' instrumental music. Therefore, this book describes not so much continuities than the changes which the use of the term 'sonata' underwent through the centuries – putting those changes into their historical context. The first chapters traces the various definitions and connotations of the term 'sonata'. The second chapter is concerned with form: from the canzona form in the 17th century to dance forms and contrapuntal forms in the 'sonata da camera' and 'sonata da chiesa' around 1700; from those forms to the infamous 'sonata form' with all the myths and misunderstandings by which this term is surrounded; and up the serial, historicising and postmodern structures which characterise the sonata of the 20th century. The third chapter is concerned with functions and aesthetics: Who composed sonatas and for whom were they composed, who played them. bought them, listened to them? The fourth and final chapter looks at scoring. What, exactly, is a 'trio sonata'? What reasons are there for the late arrival of the keyboard sonata in the mid-17th century and what caused its triumph in the 19th? What distinguishes a sonata for piano and violin from one for violin and piano?