Solfeggietto (H 220, Wq. 117: 2) is a short solo keyboard piece in C minor composed in 1766 by Carl Philipp Emanuel Bach. According to Powers (2002:232) the work is correctly called Solfeggio, although the Solfeggietto title is widely used today. Owens refers to the work as a toccata.
The work is unusual for a keyboard piece in that the main theme and some other passages are fully monophonic, i.e. only one note is played at a time. The piece is commonly assigned to piano students and appears in many anthologies; pedagogically it fosters the playing of an even sixteenth note rhythm by alternating hands.
This piece is easily Bach's best-known, to the point that Paul Corneilson's introduction to The Essential C.P.E. Bach is subtitled "Beyond the Solfeggio in C Minor". Owens also describes it as C. P. E. Bach's most famous work.
The work is often performed by left-hand alone. 
The piece was used as a main theme in the 1990 educational computer game Treasure Mountain!.