For those of you who don't know, Vocaloid is a voice synthesizer software to create artificial singers called vocaloids, these digital popstars have artificially created voices or vocaloid voices. I know this is confusing, so.let me offer a breif vocabulary lesson.
Vocaloid - voice synthesis spftware
vocaloid - artificially created voice
vocaloid - digital popstar with an artificial voice
One of the most famous vovaloids is Hatsune Miku, but my personal favorites are Kagamine Len, and Megpoid Gumi. Heres a few videos to demonstrate