Cardinality

The number of Tuples in a Relation's Body, or more simply the number of data rows in a table.

Example:

UserId UserName Email Password
1 AJones alex.jones@abc.com ########
2 BSmith bob.smith@def.com ########
3 CBloggs chris.bloggs@xyz.com ########

From the table above the Cardinality would be 3.