At this stage it will be helpful to learn the popular octaves that can be played within open D tuning. The sixth, fourth and first strings share the same note at the same fret and the fifth and second strings share the same note at the same fret. The following example, played in open D tuning features octaves.
The tremolo arm or "Whammy Bar" can be used to produce a variety of sounds on the electric guitar, ranging from subtle vibrato on chords to dramatic bends, harmonics and "dive bombs".
There are several different types of whammy bars fitted to all types of electric guitars. These include Fender, Bigsby and Floyd Rose. Use of the whammy bar was first thoroughly explored by Jimi Hendrix, who brought many new sounds into music.