Final Fantasy XI (ファイナルファンタジーXI Fainaru Fantajī Irebun?), also known as Final Fantasy XI Online, is a MMORPG developed and published by Square (later Square Enix) as part of the Final Fantasy series. It was released in Japan on May 16, 2002 for Sony's PlayStation 2, and for Microsoft's Windows-based personal computers in November of that year. The PC version was later released in North America on October 28, 2003, and the PlayStation 2 version on March 23, 2004. In Europe, only the Windows version was released, on September 17, 2004. An Xbox 360 version was released worldwide in April 2006 for all regions, as the system's first MMORPG and first cross-platform MMORPG. All versions of the game require a monthly subscription to play, however the Xbox 360 version does not require an Xbox Live Gold account.
The story is set in the fantasy world of Vana'diel, where player-created avatars can both compete and cooperate in a variety of objectives to develop an assortment of jobs, skills, and earn in-game item rewards. Players can also undertake an array of quests and progress through the in-game hierarchy and thus through the major plot of the game. Since its debut in 2002, four expansion packs have also been released, with a fifth in development, along with six add-on scenarios. Each expansion pack and add-on brings a new major storyline to the Final Fantasy XI world, along with numerous areas, quests, events and item rewards.
In 2006, between 200,000 and 300,000 active players logged in per day, and the game was the dominant MMORPG in Japan. In 2008 Square Enix noted that Final Fantasy XI had a strong user base of around 500,000 subscribers, and in April, 2009, announced that the total number of active characters exceeded 2 million for the first time. Square Enix president Yoichi Wada announced in June, 2012, that Final Fantasy XI had become the most profitable title in the Final Fantasy series.