A singer is a musician who uses his or her voice to produce music. Usually, singing refers to vocal melody only, though vocalist is a similar term which also encompasses non-melodic sounds and effectively includes anyone using their voice as part of a musical composition, including spoken word, Death grunt, Hardcore screaming, and rapping.
According to Alfred Alexander (formally a ENT consultant to the home office), "a singer is a person of adequate musicality, who is gifted with a voice of such power and beauty that competent judges can recommend singing as a career". Alexander belives that 1 in 50,000 in the UK possess such gifts, which means in England (800,000 births a year average) 16 people are born with such a voice a year, making 500 "first class voices" active in any particular generation (taken as 30 years) at any one time.