What is the name of the default theme that is installed with Windows XP?

The default theme installed with Windows XP is called Luna. It was introduced with Windows XP and aimed to provide a modern and visually appealing user interface. Luna featured a blue color scheme, rounded edges, and a simplified design, making it a significant departure from the previous clunky and outdated Windows interface. It became synonymous with the Windows XP experience and was widely recognized as its default theme.