Barbershop 
Close, unaccompanied, four-part vocal harmony. Barbershop is a uniquely American style of singing. The lead (melody) predominates; bass (lowest part) provides the foundation; tenor (highest part) harmonizes, lightly, above the lead; and baritone (surrounding the melody) sings either above or below the lead, as needed, to complete the chords.

Overtone                   
Overtones can often be heard when barbershop chords are well-balanced and blended. These notes are not sung, but are created by the harmonies and they appear to add a fifth or more notes to the chord. Barbershoppers strive to create overtones, resulting in what they call “expanded sound.”

Tag
Ending of a song. Often tags are sun by barbershoppers who’d prefer to enjoy the sounds produced at the end of a song, rather than sing the entire arrangement. Tags are easy to learn and fun to sing, and will often keep barbershoppers up ‘till the wee hours of the morning, meeting new friends, sharing new songs, and harmonizing together.

Woodshedding  
Singing a song “by ear” and improvising to harmonize. This activity
represents the origins of how barbershopping began, is fundamental
​to the art, and is the essence of barbershop singing.