Vibrato is a technique where the left hand moves the fretted string rapidly up and down small distances towards adjacent strings. Vibrato helps to sustain a note and can make that note more interesting in a solo. Vibrato is indicated by a wavy line written above the note and tab. Vibrato can be applied to any fretted note and played by any left hand finger (most commonly the first, second and third fingers).
The following lick uses the vibrato technique.
This example uses vibrato on bent and standard fretted notes.