Tagging is a very powerful way to create customer segments and then track the activity of members of these segments in other reports. Tags can be generated from most reports. Additionally, you can tag customers from the Customer Directory. As an example, generate a Promotions Redeemed report, and then Tag Results by clicking the button to the far right, under the Date Range.
Individual customers can also be added to an existing tag via the Booker profile card.
Once you have created your segments using tags, you can take those segments and apply them to other reports, like an attendance report, to see revenue generated from the Promotion.
Also note:
Tags are exportable ... so if you see a report that does not provide the export capability, Tag it, and then export the results.
Tags can be synced with MailChimp lists ... see this article