D7-shape Chord
The movable dominant seventh with a root on the fourth string.
Dominant seventh chords add a little tension to a chord progression, creating a desire for movement. The D-shape dominant seventh chord (D7 for short) adds a minor seventh interval to the D-shape major triad.
The core D7 shape
This is the movable version of the familiar open D7 chord, fingered xx1324. Compared to the D major shape, the R on the second string drops back two frets, becoming the ♭7. That note is the main feature of this chord, so make sure it rings out.
Incidentally, jazz players know this grip as a drop 2 voicing: the chord tones are stacked R5♭73 on four neighboring strings, the same construction as the A7 drop 2 grip. It's part of a whole family of seventh chord voicings on the highest-pitched strings.
Study and practice
Learn the chord grips
Master the D7 chord using the exercises described in How to Master New Chord Grips.
Alternate between major and dominant seventh
Practice switching between the D-shape major and dominant seventh chords.
V7-I cadence
(Tip: Change key in settings)
Practice switching between the D-shape V7 and I chords of a key. This is a very common chord change, known as a perfect cadence.