There are five types of 7th chords and arpeggios. In the diagrams below there are four ways to play each arpeggio

Major 7

The major 7 chord, or arpeggio, consist of the intervals 1, 3, 5, and 7. You will see various ways of writing nomenclature for each chord. Using C as an example, it will be written CMaj7, CM7, C∆, or C∆7.

Dominant 7

The Dominant 7 chord, or arpeggio, consist of the intervals 1, 3, 5, and ♭7. Using C as an example, it will be written C7.  It is important to remember the Dominant 7 does not have a 7. It has a ♭7. This is a point of confusion for countless students.

Minor 7

The minor 7 chord, or arpeggio, consist of the intervals 1, ♭3, 5, and ♭7. Using C as an example, it will be written Cm7, C-7, or Cmin7.

Half diminished 7 

The half diminished 7 chord, or arpeggio, is also referred to as the minor 7♭5. It  consist of the intervals 1, ♭3, ♭5, and ♭7. Using C as an example, it will be written Cø, Cø7, Cm7♭5, C-7♭5, or Cmin7♭5.

Diminished 7 

The diminished 7 chord, or arpeggio, consist of the intervals 1, ♭3, ♭5, and  ♭♭7 (double flat 7 which is the same interval as a 6). Using C as an example, it will be written C º7, or C dim7.