Just remember, these are all notes from the scale – hence you'll encounter both major and minor 3rds as you ... This is the augmented 4th, D#, in action. A 7th chord is a simple extension ...

And the six chords available in each key let you play every major and minor chord ... an Eb (pronounced E Flat) major chord is sonically the same exact thing as a D# (pronounced D sharp) major ...