The appoggiatura · Ornaments · Music theory
The appoggiatura is a small note, a 2nd away from the main note, that falls on the beat and takes part of its value: half if the note is plain and two…
The appoggiatura
The appoggiatura is a small note, a 2nd away from the main note, that falls on the beat and takes part of its value: half if the note is plain and two thirds if it is dotted. It creates a small dissonance that resolves into the main note.
The acciaccatura has a slashed stem. It is played very fast, right before the main note, which hardly loses any time.
Long and short, in history
The long appoggiatura leans on the ornamented note itself, and its dissonance is what is expressive: it is usually approached by leap and left by step in the opposite direction. The acciaccatura, in the 18th century, was something else: a note struck with the chord and released at once.
In the 19th century it came to mean a very short note, written with a stroke. An unslashed grace note can mean different things depending on the composer, and in Classical music it often has a value that does not match its written shape: this has to be deduced from the context.