Luna was the Microsoft codename for the new Windows XP interface. It's based heavily on concepts first explored in MSN Explorer. It has big icons similar to Aqua, and other "modern" computer user interfaces. It is for the first consumer OS based on the Windows 2000 kernel. IT has many enhancements and built in extras for things such as Windows Media Player, IE, and other Windows-esque enhancements. Windows now has a more distinct look and feel.

It is the biggest UI upgrade in Windows since Windows 95 (over Win 3.x), and takes heavy advantage of MSN services.