Some important chords you should know, and how they work

Part 1:

The list of chords, their positions and inversions is pretty exhaustive and seemingly endless. Instead of writing a huge chart for you to try and memorize, we’re going to save a little time and space (and avoid possible carpal tunnel) by keeping this list basic, and throwing in a little bit of theory so you understand how these chords are made and how to figure out your own. (There will be a chapter explaining scales and theory in more depth later on)

Hopefully at this point you know a few major and minor chords. Major and Minor chords are both formed with three notes from the corresponding scale. For example, an A major is formed with the 1st, 3rd and 5th notes of the A major scale, listed here:

A B C# D E F# G#
1 2 3   4  5 6   7
T T S   T  T  T  S

T=Whole Tone, S=Semitone

While the A minor is formed with the 1st, 3rd and 5th notes of the minor scale:

A B C D E F G#
1 2 3 4  5 6 7
T S T T  T T S

All other chords are basically extensions or augmentations based on those three notes.
Confused? Not for long.

A 7th chord is a four note chord, it can be major or minor. The added note is the seventh note of the scale. Staying with our trusty A major chord and scale, add a G to it and we have the A7.

If we add the 6th note of the scale, in this case the F#, we have the A6.

But, if there are only seven notes in a scale, how do they come up with these crazy 9th and 13th chords? Here is the trick. When you count past 7 you get to the root again an octave higher. Staying with our example the 8th note is A, counting up from that the 9th note would be B. Just remember, anything you add from this point will be based on the 7th chord. If we wanted to make an A9 we would have this five note chord:

To make it an A13 chord we add the note F# and have this: