BENDING and vibrato
Pick the note and then bend up a quarter tone (a very small amount). Sometimes referred to as a blues curl.
The fretting hand vibrates the note by small bend ups and releases. The last example uses the vibrato bar.
Bend up to the pitch shown in the brackets, then re-pick the note while holding the bent note at the new pitch.
Bend up from the 5th fret to the pitch of the 7th fret note, then pick it and release to 5th fret note.
Fret the start note (here, the 5th fret) and bend up to the pitch of the bracketed note, before releasing.