There are three types of Media libraries in OnSite.
1) The Shared Media folder is used for media to be shared with all users, by default. Permissions can be added to sub-folders to restrict access to specific Site Groups. Shared Media can be published to a Site.
2) The Template Media folder is used to store media for use within templates. For example, an image of a logo for use across multiple templates. Template Media can not be published to a Site.
3) The Media tab outside of Admin mode is a Site-specific media library, available only to users with access to that Site.
The Media tab enables OnSite users to manage their own media. Switching Site Groups will display the Media library for that Site Group.
Above the media is a folder breadcrumb that displays the current library and also allows the user to navigate to different levels of the folders.
This Media can be published to a Site.