Tags enable you to identify your resources in new ways. Tags are like keywords or labels, and they allow you to rearrange your view of resources within XenCenter depending on criteria that are important to you, such as application, location, cost centre, owner, or lifecycle stage.
You make up tags when you need them and you can use as many as you like, and you can build searches based on your tags, for example "all Windows 7 test machines located in Cambridge".
Click on the General tab for a resource to see the tags currently assigned to that resource and to add and remove tags.
The simplest way to assign an existing tag to a resource is by dragging and dropping it onto the tag in the Resources pane. You can drag and drop resources from within the Resources pane on the Tags group, and also from the search results list on the Search tab.
You can also assign an existing tag or a new tag to a resource using the Edit tags dialog box:
To untag (remove a tag from) a resource, in the Navigation pane, click Organization Views and then click Objects by Tag. Select the resource that you would like to untag, right-click and then select Untag object.
You can also untag a resource using the Edit Tags dialog box: