Carl Philipp Emanuel Bach

The second surviving son of Johann Sebastian, and for most of the eighteenth century the more famous of the two. Haydn and Beethoven both studied his keyboard music closely, and it sounds like neither his father's nor anyone else's.

The keyboard sonatas are the body of it, and they are genuinely useful teaching repertoire — comparable in difficulty to Haydn's, more unpredictable, and far less played. The Solfeggietto in C minor is the one piece of his that everyone has met, usually early. His treatise on keyboard playing is still the primary source for how this music was performed.

Works carry Wq. numbers from Wotquenne and H. numbers from Helm, and editions use one or the other or both, so the same sonata appears under two identifiers. Where a listing gives both, they are the reliable way to confirm what you are buying.