Luna (the Moon in Latin and various other languages) is the codename for the default visual theme of Windows XP. First introduced in Whistler Build 2428, replacing Watercolor theme.

Officially known as Windows XP style, the theme is available in three color schemes: blue (default), olive green(Homestead), and silver(Metallic). Some users who did not like the theme characterised it as a "Fisher-Price interface". Luna theme, along with Royale(XP MCE and Tablet) was removed in later versions starting Windows Vista.