Noun
the sharps or flats that follow the clef and indicate the key
Source: WordNetThe first line is the DNA of the poem; the rest of the poem is constructed out of that first line. A lot of it has to do with tone because tone is the key signature for the poem. The basis of trust for a reader used to be meter and end-rhyme. Billy Collins
I thrive on change. That's probably why my chord changes are weird, because chords depict emotions. They'll be going along on one key and I'll drop off a cliff, and suddenly they will go into a whole other key signature. That will drive some people crazy, but that's how my life is. Joni Mitchell
Conversely, adding a double sharp to any other note not sharped or flatted in the key signature raises the note by two semitones with respect to the chromatic scale. Source: Internet
Although a key signature may be written using any combination of sharp and flat symbols, about a dozen diatonic key signatures are by far the most common, and their use is assumed in much of this article. Source: Internet
A key signature designates notes that are to be played higher or lower than the corresponding natural notes and applies through to the end of the piece or up to the next key signature. Source: Internet
A sharp symbol on a line or space in the key signature raises the notes on that line or space one semitone above the natural, and a flat lowers such notes one semitone. Source: Internet