Custom Objects allow you more control over your Net-Results marketing use. Think of Custom Objects as custom data tables, that leverage your custom data to control email campaign participation, drive automated workflows, list membership and other actions.
Custom Objects allow for many-to-one relationships with both Accounts and Contacts in Net-Results. For example, you could store many purchases that were made by a given Contact or Account, and then leverage the data from those purchases in Segments.
Custom Objects are similar to Custom Fields you must define a Custom Object before you begin storing data in it. Unlike Custom Fields, a Custom Object can consist of many fields that all relate to your object.
A good example of this is a Tour Company. Your customers may register for one, or multiple tours. Each one of those tours has a name, departure date, and a duration in hours. With Custom Objects, you can store as many tours as are needed for any given Contact.