Zune was a media management software for Microsoft Windows that functions as a full media player application with a library, an interface to the Zune Marketplace, and as a media streaming server. The software is used to sync with all devices with Zune functionality including the Zune 4, 8, 16, 30, 80, 120, Zune HD, Windows Phone 7, and Microsoft Kin. Zune devices work exclusively with the Zune software, which applies many design principles of Microsoft's Metro design language.