Xbox Game Studios (previously known as Microsoft Studios, Microsoft Game Studios, and Microsoft Games) is an American video game publisher based in Redmond, Washington. It was established in March 2000, spun out from an internal Games Group, for the development and publishing of video games for Microsoft Windows. It has since expanded to include games and other interactive entertainment for the namesake Xbox platforms, other desktop operating systems, Windows Mobile and other mobile platforms, web-based portals, and other game consoles.

Xbox Game Studios, alongside ZeniMax Media and Activision Blizzard, are part of the Microsoft Gaming division led by Phil Spencer, who is chief executive officer of the division.

Reference: Wikipedia