What is "bent note"

A bent note is a musical note that is varied in pitch. With unfretted strings or other continuous-pitch instruments such as the trombone, or with the human voice, such variation is more properly described in terms of intonation. Bent notes are commonly played on fretted instruments, literally by bending the string with excess finger pressure, or on free reed instruments such as the harmonica, by using excess air pressure to overblow the reed. On brass instruments such as the trumpet, the note is bent by using the lip.

The bent note is commonly found in various forms of jazz and blues.