Appeals are stored in the Appeals dataset. As with the constituent record and other dataset appeals, many have their own custom fields and tabs for tracking data around a specific appeal.  

Appeals are linked to gifts through the Appeal section on a gift.

With the gift to appeal link created, any record the gift has been made for can now be linked to that appeal in the dataset. This means information about the appeal can be included in any queries, reports, or reconciliations the gift is a part of (person, dataset, donor, etc.).