Vocaloid is a singing synthesizer application, with its signal processing part developed through a joint research project between the Pompeu Fabra University in Spain and Yamaha Corporation, who backed the development financially—and later developed the software into the commercial product "Vocaloid". The software enables users to synthesize singing by typing in lyrics and melody. It uses synthesizing technology with specially recorded vocals of voice actors or singers. To create a song, the user must input the melody and lyrics. A piano roll type interface is used to input the melody and the lyrics can be entered on each note. The software can change the stress of the pronunciations, add effects such as vibrato, or change the dynamics and tone of the voice. Each Vocaloid is sold as "a singer in a box" designed to act as a replacement for an actual singer. The software was originally only available in English and Japanese, but as of Vocaloid 3, Spanish, Chinese and Korean will be added.
The software is intended for professional musicians as well as light computer music users and has so far sold on the idea that the only limits are the users' own skills. Japanese musical groups Livetune of Victor Entertainment and Supercell of Sony Music Entertainment Japan have released their songs featuring Vocaloid as vocals. Japanese record label Exit Tunes of Quake Inc. also have released compilation albums featuring Vocaloids. Artists such as Mike Oldfield have also used Vocaloids within their work for back up singer vocals and sound samples.