Singing is the art of making music with the human voice. The extent to which the vocal chords can be manipulated and controlled helps determine the beauty and power of the sound produced. The music produced by singers, particularly a poem set to that music, is a song; singing with the lips closed is called humming.
Singing is an innate talent to some extent, but, since it involves parts of the body that can be exercised and trained, and the employment of certain musical skills, such as recognising rhythm, melody and harmony, people with even modest amounts of talent can be taught to sing fairly well. There are very few people who can speak who cannot be trained to sing, even those with so-called tone deafness can often learn to sing on pitch if they are willing to invest the time and effort.
Western music classifies human voices into different voice parts, based on the natural range of tone in a person's voice. In general, female voices sign one full octave above male voices, although there are women with naturally low voices who can sing comfortably in the male range, and men who can comfortably reach into the female range. People can be taught to extend the range of tones they can sing, but a person's voice part delineates the range of notes they sing most comfortably.
These are the main divisions; voices are divided into sub-ranges as well.
In addition to ranges, voices are characterised according to style.
Birdsong is best known. Alas, birds rarely sing because they are happy, but as a challenge or invitation.
The vocal abilities of non-human primates are relatively unimpressive in comparison, with gibbon songs being a rare exception. They use songs also to protect themselves against predation. [1].
Whales and other cetaceans have complex song, probably both for communications and echolocation. Alan Hovhaness wrote a haunting symphonic piece featuring whalesong, "And God Created Great Whales; Concerto No. 8 orchestra & taped whale sounds, Op. 2.