A crossfoot is a summarization of the column totals in a ledger. The intent of crossfooting is to ensure that all column totals summarize to the grand total. If not, then there is an error in the column totals or the grand total that must be corrected. This is an essential tool of the auditor, to ensure that reports summarize correctly.
The concept is also used when manually verifying that a newly-designed report operates as expected. Crossfooting verifies that the automated totaling functions in a report are working as expected.