Franz Joseph Haydn, born on 31 March 1732, died on 31 May 1809 was an Austrian composer of the Classical period. He was instrumental in the development of chamber music such as the string quartet and piano trio. He is regarded as the "father of the symphony" and the "father of the string quartet" for his more than 100 symphonies and almost 70 string quartets. Haydn also produced numerous operas, masses, concertos, piano sonatas and other compositions. Haydn spent much of his career as a court musician for the wealthy Esterházy family at their Eszterháza Castle. His music circulated widely, and for much of his career he was the most celebrated composer in Europe. He was a friend and mentor of Mozart, a tutor of Beethoven, and the older brother of composer Michael Haydn.