Vocaloid is a singing synthesizer application first developed at the Pompeu Fabra University in Spain and backed financially by the Yamaha Corporation.^[1] The software enables users to synthesize singing by typing in lyrics and melody. It utilizes Yamaha's Vocaloid 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". The software is available in English and Japanese, although a Chinese version was produced for Sonika.
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.^[2] Japanese musical group Supercell (Sony Music Entertainment Japan) have featured Vocaloid as vocals in their songs, and record labels in Japan also have released compilation albums featuring Vocaloids.
The Yamaha Corporation announced the Vocaloid technology for the first time at the German fair Musikmesse in March 2003.^[3] The first Vocaloids, Leon and Lola, were released by the studio Zero-G on March 3, 2004, both of which were sold as a "Virtual Soul Vocalist". Leon and Lola made their first appearance at the NAMM Show on January 15, 2004.^[4] Leon and Lola were also demonstrated at the Zero-G Limited booth during Wired Nextfest and won the 2005 Electronic Musician Editor's Choice Award.^[5] Zero-G later released Miriam, with her voice provided by Miriam Stockley, in July 2004. Later that year, Crypton Future Media also released their first Vocaloid Meiko. Due to the success of placing a character on the box art of Meiko, the concept was carried over to her successor Kaito and later Vocaloids to encourage creativity, however neither Vocaloid's box art originally had the intention to represent that Vocaloid.^[6][7] Though Leon, Lola, Miriam and Meiko experienced good sales, Kaito was the only one who initially failed commercially. After interest in Vocaloids grew, Zero-G began reselling their Vocaloid products again on their website, and were considering to update their box art to match current Vocaloid trends better.^[8] As well as an update for Leon and Lola's box art, Meiko and Kaito are also reported to be in discussion for an update.^[9]

The first release based on the Vocaloid 2 engine came from PowerFX with Sweet Ann on June 29, 2007 whose boxart was based on a Frankenstein's monster.^[15] This was closely followed by Crypton two months later with the first of their "Character Vocal Series", Hatsune Miku, on August 31, 2007. Zero-G's first Vocaloid, Prima, came out on January 14, 2008 with voice of a Soprano opera singer. Internet Co., Ltd. also joined the Vocaloid development with their first Vocaloid Gackpoid on July 31, 2008, whose voice was provided by Japanese international singer Gackt. Gackpoid includes a new program, OPUS Express, for mixing vocal parts with accompaniment or phoneme data.^[16] AH Software later released their first Vocaloids on December 4, 2009 bringing the total of studios producing Vocaloids to five. As of the introduction of Bplats and Sony Music Entertainment in late 2010, there are seven studios involved with the production and distribution of Vocaloids with two involved solely in English, four solely in Japanese and one in both languages for which the software is developed.