Niente
Nothing, dying away into nothing.
What it means
Niente means “nothing” and designates, in dynamic markings, the zero point: silence. As an independent instruction the word rarely stands alone; common are the phrases al niente (“to nothing”) for a dying away and dal niente (“from nothing”) for an imperceptible arising of the sound.
In both cases what is meant is not a sudden silence but a transition. The sound is to cross the boundary between the audible and the inaudible gradually, so that the listener cannot exactly determine the moment of beginning or ending. Herein lies the difference from a cutoff or an entrance out of silence.
The marking concerns only the dynamics. Words such as morendo and smorzando additionally pull back the tempo.
In the notation
Niente appears as a word at the end of a hairpin or as a sign: a small circle or the digit 0 at the tip of the hairpin. With dal niente, the sign stands at the beginning of an opening hairpin. Both spellings are equivalent; which one an edition chooses is a matter of habit.
Musical use
Shaping the boundary between sound and silence belongs among the expressive means of twentieth- and twenty-first-century music and is notated there with signs of its own. In older music the same concern is found, but described with words — perdendosi, morendo, estinto. It is used at movement endings, with sustained notes, and where a sound is to arise out of silence.
The marking often stands with al.
Performance practice
Plan the path to silence over the whole stretch and keep reserve until the very end. Take care that tone and intonation remain stable at the extreme soft end. With dal niente, start so that the first moment does not become audible as an attack — for string players a very slow bow helps, for wind players an attack without tonguing. And give the transition time: reached too quickly, the silence seems like a cutoff.