In addition to sonatas, variations, and concertos for piano and orchestra, Mozart wrote numerous works for solo piano: fantasias, rondos, adagios, and other assorted pieces of short and moderate length. We don't know exactly why these works were written, but we know that Mozart had to come up with new material for his many public and private appearances as a composer and performer. In those days composers were usually performers as well. Any composition was also a potential source of income from publication and from patrons and friends to whom the works were dedicated. But no matter why these marvellous works were written, we are lucky to have them.