To fix a wannabe's voice. Someone who can't sing to save their lives but do it anyways and make it catchy. It is taking over the musical world. Some singers who use it are Ke$ha, Katy Perry, Jason Derulo, Korean groups like T-Ara, too many to count.

Pitch correction software specifically for vocals that makes up for a lack of natural singing talent. 90% or more of all "professional" recordings use this software.
An extreme example is that horrific Cher song from a few years back, and the Kid Rock song where is voice is all fucked up. Used in moderation it can hardly be heard except by a trained ear.

The software Katy Perry uses to make her albums bearably in tune.

Someone who uses autotune to create a song. Frequently used by "rappers" but really shouldn't be rappers but should be known as a new genre called "Autotune"

Autotune is simply a piece of technology made by the dark lord Lucifer to snare the souls of all man kind,since autotune was taken up by a Mr T-Pain people have been dick riding this software and selling their souls to the dark angel at the same time, much to the amusement of every Rock'n'Roll fan. Kanye West devoted an entire album(808 & Heartbreak) to this piece of shit and the gates of hell opened like Paris Hiltons devil snatch and ever since autotune has been a means to sell albums to teenagers begging to fit in to their 'click'. With a billion Chinese people in the world loving this crap im sure we will have to bear with it for years to come.God I only hope that I die before Nickelback start using it.

-TPain's voice in songs

The means by which average people can become godly singers instantly. No musical knowledge is required, just loop a beat and sing away!