Tags have two purposes. They can help you to organize your devices and event monitors. For example, if you add the tag "type=database server" to a set of devices you can then create an event monitor that will check only those devices that have that tag. Just use the dropdown option at the top of the device chooser in the event monitor settings. Secondly you can include tag values in your notifications. Just edit your notification template to include the text "%%devicetag=tagname%%" or "%%eventmonitortag=tagname%%" and it will be replaced with the tag's value. For example you could assign a tag "contactname=John Smith" to a device and then edit your template to include ""%%devicetag=contactname%%". Then when you receive an e-mail notification it will include "John Smith" as the contact name. And of course, each device can have a different contact name according to the tag you have assigned.

Optional. You can use the Notes field to enter freeform text about the event monitor. For structured information such as technical contacts, physical locations, etc., consider using tags instead.