Luna

Luna is the visual style that shipped with Windows XP (except the Starter SKU and the Itanium 64-Bit releases) and some betas of Whistler (starting with build 2415 and then from build 2428 onwards). It was also available in all Longhorn builds up to build 5048 (although from build 4015 through build 4093, the taskbar and sidebar would still display in the Longhorn Plex/Slate style unless the sidebar is disabled). Notably in Longhorn, the Windows logo on the Luna 'start button' is all white rather than colored as it was in Windows XP. It is known as "Windows XP theme" in the Control Panel.

Luna in Windows XP (build 2481 onwards) had three color schemes: Luna Blue (the default), Luna Silver, and Luna Olive Green. While Royale, Royale Noir, Zune, and Embedded are often considered separate themes, they are technically subsets of Luna. This video shows all the Windows XP themes.