The absence of unintended changes or errors in some data. Integrity implies that the data is an exact copy of some original version, e.g. that it has not been corrupted in the process of being written to, and read back from, a hard disk or during transmission via some communications channel.
Integrity may further imply that the information represented by the data has been validated, i.e. verified to conform to certain constraints, e.g. a date's year, month and day parts are within the appropriate ranges and the date actually exists.