Cross filters can be defined to only show parent records that have or do not have a related child record.
Classic filter operators include Equals, Greater than, Less than, etc … The key features of cross filters are the operators WITH and WITHOUT.
Therefore, it is possible to exclude certain results: lost any Account without a related Contact.
Subfilters can be added to further filter by field on the child object. Subfilters allow, for example, to list in a report just the Accounts without closed won opportunities.
If you have a cross filter of Accounts with Opportunities, you can add an opportunity subfilters to see just those opportunities that are not gained allow reports to appear in a report without any won opportunities gained.
Example: We want to target in our next campaign, accounts that have no ongoing business. To bring out those accounts that have no related open opportunities, we will need to create a report showing the accounts with no current opportunities.
NB: you can define up to 3 cross filters per report, each cross filter can have up to 5 subfilters. Subfilters apply only to the child object.