Another important chord type is the Dominant 7th chord, commonly called a 7th chord. 7th chords are common in Jazz, Blues, Rock, Funk, and many other styles of music.
C
A dominant 7th chord (usually just called a 7th chord) is created by adding a flattened 7th degree to any major chord. E.g. a C7 chord contains the notes C, E, G and Bb (1, 3, 5 and b7). Shown below are some common open dominant 7th chord shapes.
The following example should help you become familiar with these basic 7th chord shapes.