A View: A virtual relation that does not actually exist in the database, but is produced upon request by a particular user, at the time of request.
The dynamic result of one or more relational operations operating on the base relations to produce another relation.
Provides a powerful and flexible security mechanism by hiding parts of the database from certain users.
Can be defined over several relations with a user being granted the appropriate privilege to use it, but not to use the base relations.
Using a view is more restrictive than simply having certain privileges granted to a user on the base relation(s).