Since the early 19th century, singing voices have usually been classified in six basic types, three male and three female, according to their range; some opera boasts a seventh voice type, the countertenor, as well:
SOPRANO, the highest voice type, normally possessed only by women and boys.
MEZZO-SOPRANO, the voice type lying below the soprano and above the contralto; the term comes from the Italian word “mezzo,” meaning “middle.”
COUNTERTENOR, a male voice type with a range comparable to that of the female mezzo-soprano, achieved by singing in the falsetto (or “head voice”) range.
CONTRALTO, the lowest female voice, also called an alto.
TENOR, the highest standard voice type in adult males.
BARITONE, the male voice lying below the tenor and above the bass.
BASS, the lowest voice type.