Turn
Ornament around the main note and both auxiliary notes.
What it means
The turn (German Doppelschlag) plays around the main note with its two neighbouring notes. The usual form runs from top to bottom: upper auxiliary note, main note, lower auxiliary note, main note. With the inverted turn the direction is mirrored — lower auxiliary note first.
The Italian designation is gruppetto, the German Doppelschlag; all three mean the same figure.
The turn is to be distinguished from the trill, which alternates only between the main note and the upper auxiliary note, and from the mordent, which asks for a single rapid alternation with the lower auxiliary note. The turn is the most complete of these small figures, because it involves both neighbouring notes.
Whether the auxiliary notes lie a semitone or a whole tone away follows from the key; deviating cases are indicated by small accidentals above or below the sign.
In the notation
The sign resembles a lying S and stands above the note. If it stands directly above the notehead, the figure begins with the note; if it stands between two notes, it is executed after the first note has sounded. The mirrored sign means the inverted turn. Accidentals above concern the upper, below the lower auxiliary note.
Musical use
The figure belongs to the fixed stock of melody of the Baroque, the Viennese Classical period, and the Romantic period. It enlivens long notes, adorns goal notes, and often stands at phrase ends and in cadences. In slow movements it is played out and acts as a melodic turn, in fast ones it remains a short ornament.
Other names
In German the ornament is called Doppelschlag, in Italian gruppetto. The inverted turn, which begins with the lower auxiliary note, is called inverted turn in English.
Performance practice
Adapt the speed to the tempo and the character: in slow movements the figure may be given time, in fast ones it stays brief. Take care that the main note keeps its position and the ornament does not cover it. Check the accidentals at the sign. And decide on the execution beforehand instead of looking for it while playing — the figure almost always fails from indecision.