What audio artifact is caused by incorrect pitch correction, and how can it be avoided?

The audio artifact caused by incorrect pitch correction is often referred to as the "Auto-Tune effect" or "chipmunk effect", although those are somewhat colloquial terms. More technically, it's a form of quantization distortion characterized by unnatural, stepped pitch transitions and a lack of smooth, organic vocal movement. This artifact occurs when pitch correction software (like Auto-Tune or Melodyne) is used excessively or with inappropriate settings. The software forces the vocal performance to sn....