Drop 2 voicings are some of the most important chord shapes you can learn. These shapes are used by all sorts of guitar players to provide an easy way to learn chord voicings all over the neck.
We create a drop 2 voicing by dropping the second voice down to the bottom of the chord. For example a C major seven chord has the notes C, E, G, B. We can drop the G down to the bottom of the chord to give a voicing of G, C, E, B.
We have three sets of voicing for each chord type. There are chord shapes for the low, mid and high strings. It is important to learn all three types so that you can call on them when required. Try playing some simple chord progressions and see if you can switch between the chord shapes in different parts of the fretboard.