Barbershop music features songs with understandable lyrics and easily singable melodies, whose tones clearly define a tonal center and imply major and minor chords and barbershop (dominant and secondary dominant) seventh chords that resolve primarily around the circle of fifths, while making frequent use of other resolutions. What sets barbershop apart from other musical styles is the predominant use of the dominant-type seventh chords. Barbershop music also features a balanced, symmetrical form and a standard meter. The basic song and its harmonization are embellished by the arranger to provide appropriate support of the song's theme and to close the song effectively.”