Initially, Auto-Tune is vocal corrector software for singing in tune. But, when you push the settings to the extreme, the processing, so far transparent and natural, takes on an artificial character, giving the voice a "metallic" appearance. It is often associated with singer Cher and rapper T-Pain, who popularized its use, but many other artists use it, openly or not, especially in rap and electronic music.
Auto-Tune is an original production of Antares Audio Technologies, but since 1997 a large number of software has this function, as well as "stand-alone" devices. As competing software, we can cite Melodyne (en), V-Vocal or VoiceWork. — Wikipedia.