One of the most famous kind of singer in the Opera´s world is the one known as Soprano. Curiously, almost 70% of the women population in the world has this kind of voice, this is because the women have an acute voice as the children also have.
And so the soprano concept says that is the musical term for the most acute voice in the human register. It has specific attributes such as clear and brilliant tone of voice, it use to lead the melody.
For historic files, the men can reach this kind of voice, in the antiquity only the castrati men can keep the acute voice and sing as a soprano, but nowadays, a men can sing as a soprano due to a peculiar development of his fonetic system, this kind of men is denominated countertenors.
Nowadays the use of the soprano´s song is not just for the opera music,eventually some methal and rock singers have this kind of voice, as a consequence it brings to this music type a singular attribute, which in my opinion suits perfectly each other and help to extend the use and mix of this kind of music (opera or classic as you wish to name it) with the enormous variety of music all over the world, giving the chance of create new types of music at the same time.
Finally we can mention that under the soprano´s classification are many others which vary in the strenght or acuity of the voice as its purposes for the opera´s musicals.