Vocaloid is a singing synthesizer, which allows the user to place sounds in a string of words and make a their chosen Vocaloid sing. Each Vocaloid has their own vocal library, which contains syllables sampled from real people. Vocaloids where first developed by Yamaha in march 2000. Since then, Vocaloid 2, and Vocaloid 3 have been released. There are many Vocaloids now, including Vocaloids developed in other countries such as England, (Engloids) and China.
The program is intended for musical professionals, and has been used by many companies and music bands such as Supercell of Sony Music Entertainment Japan as backing vocals for some of their songs.

 

In this website there are pages for each of the most popular Vocaloids, with information about their release date, voice actor/actress, available appends etc.