I've been teaching myself to play guitar without any formal instruction. Occasionally, in a tab I'll find a new chord labeled somewhere along the lines of "Cadd9" or "Dsus4". What do these mean?

I've tried searching online, but all I've found are websites showing how to play these chords.

3 Answers 3


add= addition onto chord

Cadd9 = add ninth from root note onto C triad = CEGD

sus= suspended chord

Dsus4= D triad take away major third and add a perfect 4th i.e. DGA


The answer above explains how those two specific chords are built and spelled. These are extended chords in the first instance and suspended chords in the second instance. If you are interested in studying how triads, extended chords and altered chords are built and spelled, I recommend books about harmony and music theory. There are books that are above many folks understanding, but there are also books written in easily understood language and form. They can give you answers to many of your questions and a new understanding of the art form. Personally, I love studying the stuff.

  • I'm not sure that a sus chord qualifies as an alteration: although the fourth degree is a semitone above the major third it is also diatonic. Commented Mar 28, 2018 at 6:26
  • I agree with everything here, but I might suggest starting with the study of scales. The numbers in the chords the OP gave are related to the scales, after all.
    – scott
    Commented Mar 28, 2018 at 16:25
  • @AreelXocha -- it doesn't seem unreasonable to me to call the 4th (or the 2nd) in a sus chord an alteration. Nettles and Graf notate as C7(sus4) or C7(sus2) in their The Chord Scale Theory & Jazz Harmony. In their notation scheme the bit in parenthesis indicates "any alterations or added pitches to the chord." Since the 4th isn't an added pitch, it seems that they are considering this as an alteration.
    – user39614
    Commented Mar 28, 2018 at 21:09
  • @DavidBowling, the 4th is indeed an added pitch to the chord: it's just that the 3rd has been 'subtracted'. Would you not agree? Commented Mar 29, 2018 at 1:22
  • @ Areel Xocha, Perhaps we could say the 4th has been added and the use of the third suspended, would you not agree? Commented Mar 29, 2018 at 1:32

You may find that the explanations above, as relevant as they may be, a little unsatisfying. You are obviously enthusiastic but you are leaving great gaps in your learning if you do not start learning music theory from scratch.

If you do not want a formal education, use the internet. You can choose the websites you want and can move at your own pace BUT. Be very careful which websites you get into, some on you tube are made from people who have had a few music lessons and suddenly set themselves up as teachers. Just check that the websites are from qualified teachers or organisations and your enjoyment will increase. Good luck

  • Thanks for the advice. I've been thinking lately that it would definitely help to have at least some music theory knowledge.
    – Gogeta70
    Commented Apr 6, 2018 at 16:26

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