Dominant 7th chords are a cornerstone of jazz harmony due to their ability to create tension followed by resolution. Focusing on chords like C7, G7, and A7 can provide a solid foundation. Understanding how these chords work and how to apply them in common jazz progressions, such as ii-V-I, will help you navigate the complex harmonic structures of jazz music more effectively.

Minor 7th Chords: A Melancholic Sensibility

Minor 7th Chords add a melancholic and introspective quality to the harmony, often used in a variety of emotional contexts. Good examples include Dm7, Gm7, and Cm7. Playing these chords and experimenting with different voicings can enrich your playing and help you understand how minor 7th chords can be used to evoke specific moods in your music.

Half-Diminished 7th Chords: Instability and Resolution

Half-Diminished 7th or m7b5 Chords are used to create a feeling of instability that resolves nicely in jazz progressions. Viable options include Bm7b5, Dm7b5, and Gm7b5. Understanding how to interpolate these chords and where they fit into common progressions can significantly enhance your skills in navigating the intricate jazz harmonic landscape.

Diminished 7th Chords: Colorful Passing Harmonies

Diminished 7th Chords are known for their dissonant and colorful nature, often used for creating passing harmonies. Great choices include C°7, Eb°7, and G°7. These chords can add a unique character to your playing, offering a versatile tool for improvisation and composition.

Chord Theory and Playing on the Fly

To truly master these chords and more, it's essential to understand chord theory. Start with the 9 chord, understanding how each note contributes to its '9' designation. From there, it's easier to modify chords as needed. For example, a minor 9th is created by dropping the third, while a 13th chord involves keeping the root, third, and seventh but adjusting the other notes as needed.

Remember, not all notes in a chord are necessary. The fundamental note is always required unless the bass player is covering it, the third and seventh are minor/major. Whatever is the highest number after which the chord is named should be present, and any specific modifications like a flat 5 are important. When playing with other musicians, some of the necessaries may already be covered by them.

While it's always possible to look up chords in a book, developing a sense of how to create one on the fly is a crucial skill. This will enable you to adapt and improvise more effectively, making your playing more versatile and dynamic.

Conclusion: Mastering movable jazz chords is a stepping stone to becoming a proficient jazz guitarist. By understanding and practicing these chords, you'll not only improve your technical skills but also deepen your appreciation for the rich harmonic language of jazz. Start with these essential chords and build from there, and you'll find yourself navigating the intricate world of jazz harmony with ease.