If you are referring to Logic Pro, it's a part of Logic Studio
. It's professional music editing software. It has a function to "autotune" vocals (or any other sound, really). I haven't tried that yet since I don't write vocal tracks, but I might break out the microphone one day and see how close I can come to sounding like Cher or T-Pain.
And if you're referring to "autotune," check out these:
Autotune is taking audio input and bending it to match a certain pitch. It actually has professional applications, but this autotune craze, however, is the result of people taking the concept of autotune and tweaking it so much that it makes the singer sound like a robot. It's a fad and is not what autotune was designed for.
And by the way, in the link for T-Pain above, Ellen keeps talking about "the microphone" as if that is what autotune is. It isn't. Autotune is a processor, not the dang microphone. You'd think she would have been told that before going on about it.