The Dominant 7th (Dom7) chord forms are at the core of altered and extended chords. Look at any list of altered chords  and you will notice that the Dom.7 chords have the most extensive amount of chords. They are just so accepting.

Did you know that there is a list of 16 Primary Dom7 Chords and that with these chords you can create whatever chord that you could ever need. If you include the list of how you can alter them the sky's the limit. The combinations are incredible. Not to mention the environment that these chords can generate is nothing short of amazing. With the right effects and texture you can have an inspiring soundscape to solo or jam over. 

Or quite simply your standard Blues is usually over the Dom7 chords in a I IV V progression. But we can turn that into a real "uptown blues" style. Each chord is strummed to a four count                                                                                   

G7  C9  G9  G7  C9  C7  G7  G13  D9  C9  G7  D(#9)

If you want more info about this subject download my e book here on my site under books. It is important that you have a basic grasp of music theory and knowledge of the notes on the fingerboard, as well as chord forms. In advanced material like this, it can be advantageous for you to have lessons with a competent teacher to help and guide you. To answer questions that you will have.