Tagging nodes allows you to group and run tasks on tagged nodes according to criteria that you define.
Tags are key/value pairs you can assign to nodes in order to identify and group them in different ways. You can then run tasks against nodes grouped by whatever criteria you set (e.g. operating system, physical location, environment etc.).
The Tags column on the Nodes page table contains information on the tags assigned to a particular node. Mouse over the tag icon for more information on the tags assigned to any node.