Grace note

A grace note is a kind of music notation used to denote several kinds of musical ornaments, it is usually printed smaller to indicate that it is melodically and harmonically nonessential. When occurring by itself, a single grace note normally indicates the intention of an acciaccatura. When they occur in groups, grace notes can be interpreted to indicate any of several different classes of ornamentation, depending on interpretation.

In notation a grace note is distinguished from a regular note by print size. A grace note is indicated by printing a note that is much smaller than a regular note, sometimes with a slash through the note stem (if two or more grace notes, there might be a slash through the note stem of the first note but not the subsequent grace note). The presence or absence of a slash through a note stem is often interpreted to indicate the intention of an acciaccatura or an appoggiatura, respectively. (According to the links on acciaccatura and appoggiatura... these should be reversed respectively.)

The works of some composers, especially Frédéric Chopin, may contain long series of notes printed in the small type reserved for grace notes simply to show that the amount of time to be taken up by those notes as a whole unit is a subjective matter to be decided by the performer. Such a group of small printed notes may or may not have an accompanying principal note, and so may or may not be considered as grace notes in analysis.

A grace note represents an ornament, and distinguishing whether a given singular grace note is to be played as an appoggiatura or acciaccatura in the performance practice of a given historical period (or in the practice of a given composer) is usually the subject of lively debate. This is because we must rely on literary, interpretative accounts of performance practice in those days before such time as audio recording was implemented, and even then, only a composer's personal or sanctioned recording could directly document usage.

As either an appoggiatura or an acciaccatura, grace notes occur as notes of short duration before the sounding of the relatively longer-lasting note which immediately follows them. This longer note, to which any grace notes can be considered harmonically and melodically subservient (except in the cases of certain appoggiaturas, in which the ornament may be held for a longer duration than the note it ornaments), is called the principal in relation to the grace notes.

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Wikipedia