What follows is the definitions according to Wikipedia:
There are three types of integrity that needs to be upheld in order to claim database integrity: domain, referential and entity integrity.
Domain integrityRestricts data to conform to certain data types and certain constraints, such as being within a predefined interval, in order be considered valid.
Referential integrityRequires all foreign key values to be present as primary keys in the referenced tables. In other words, there can not be any dangling references, and joining over references will not produce duplicates.
Entity integrityRequires every table to have a defined primary key. No duplicate rows can be created on the primary key.
