Tags are a way to group similar content under a single content item. Content can include pages, media, paths, tags, annotations, comments). Tagging content points a content item to other content item. For example, a page can tag media files that are related to it, and a media file can tag other related media files.
To create a tag, go to the content item that you would like tagged. Select the Relationships tab, and select Tag.
Select To make this media file a tag to choose the content items that tag the current content item. The Select Content window displays content items. Filter by page, media, etc. For example, you may wish to tag an image to other images that contain a similar subject.