Major seventh chord: A major seventh chord is similar to a minor seventh chord, but instead of having a minor third, it has a major third above the root.
Dominant seventh chord: A dominant seventh chord is like a minor seventh chord with an added major third above the root. It has a strong and tense sound.
Half-diminished seventh chord: Also known as "minor seven flat five," this type of chord consists of a root, minor third, diminished fifth, and minor seventh above the root. It has an unresolved and mysterious quality.