A playback singer is the singer who gives the voice to an actor in a film or a music album or singles. The singer and the actor are generally two different people, but there are cases when the two of them can be the same person. The actors are supposed to lip-sync with the song that has been pre-recorded by the play-back singers. These singers are chosen by the music composer based on the genre of the song and the actor who they will voice for.
The phrase “the voice suits the actor” is used for this reason- there are voices which are very close to the original voice of the actor, and hence sounds realistic. Also, there are singers who have mastered specific genres like romantic, folk, dance numbers or Sufi; singers are chosen accordingly. The playback singers don’t appear on the screen, and record the song before it is been shot for the film.
The music composer and the lyricist work together with the singer and the musicians, and the recording is done in the specialised recording studios. They have excellent voice quality and pitch and are generally versatile. Possessing the ability to modulate the voice, the singers are also aware of the basic technicalities related to music recording. They coordinate with the musicians and the actors as well for the purpose of recording the song.