What is it?
Vibrato is a wavering of pitch, produced by repeatedly bending and releasing a string.
It brings the notes to life, improving their sustain and helping to generate harmonic feedback.
How to play it
To play a note with vibrato, press the side of your first finger against the neck of the guitar. Then, twist your wrist to pivot your hand. It's not so much a motion of the fingers as it is a motion of the wrist and forearm. Your fingers move because they are attached to your hand and wrist.
Look carefully in the video what the right hand movement.
The vibrato is indicated by a wavy line placed above or beside the note.
Here we have three notes played with vibrato, the third string is pulled down while the first string up.
In the example below the A pentatonic scale is played with vibrato.
Here the vibrato technique is used on some notes in a guitar lick.