Unlike Order Categories, you can add up to 10 tags to an order. So Order Tags can be used to indicate multiple attributes for an order.
For example: If an order should be shipped by Priority Mail, you could add a "priority-mail" tag. If that same order is for a first-time buyer, you can also add a "first-time" tag. You can filter orders by either or both tags on the ORDERS page.
To add tags to multiple orders at once:
Check the box next to each order you want to tag.
Expand the More button and then select Add Order Tags.
Type the name of the tag(s) to add to each order.
If an order tag already exists on another order in your account, it will be displayed. If not, it will be created.
Click the Confirm button.
Keep in mind that only 10 tags may be added to an order. For example, if an order already has eight tags and you attempt to add three more tags, none of the three tags you specified will be added to that order.