Created by Crypton Future Media for the second edition of Yamaha Corporation's Vocaloid singing synthesizer application, Hatsune Miku is nigh-universally considered the face of Vocaloid as a whole. The software, first released in 2004, is a voice synthesizer which mimics singing using lyrical and melodic input.
While Miku is generally considered the face of the software, a number of other modules exist, often with their own characters. In fact, Miku was only the first in a 2007 series of character-themed modules designed by various licensing companies. As such, Miku typically remains linked to other Vocaloid characters, even fan-made characters such as Black Rock Shooter (a re-imagining of Miku themed after a song by Vocaloid musician Ryo), or Kasane Teto (a fan-made spoof of Vocaloid, later officially recognized by Crypton Future Media.)
Despite her status as the "face" of Vocaloid, as of 2019 Miku is technically no longer part of the Vocaloid software, as business disagreements between Crypton Future Media and Yamaha led Miku (alongside Crypton's other previously-Vocaloid characters) to be moved to Crypton's own "Piapro Studio" software.
Hatsune Miku’s first video game appearance was in the Japanese version of the online golf game PangYa, where she featured as part of a promotional campaign starting on May 22, 2008, less than a year after her first release. Her first game appearance outside of promotional campaigns was in 13-sai no Hello Work DS.
Two years after her initial release, Miku's popularity led to the creation of the Project Diva franchise, the first of which, Hatsune Miku: Project Diva, was released on July 2, 2009 by Sega. The series sees Hatsune Miku (and later other Crypton-made characters) performing popular songs created by the Vocaloid community, alongside button-based rhythm game mechanics.