MySQL 5.0 introduced support for named, updatable views. A view is a derived table—consider it as a virtual table—whose definition is stored in the database. A SELECT statement done on one or more tables (or even on views) is stored as a view and can itself be queried. Views can be used to:
Limit the visibility of columns (do not show the salary)
Limit the visibility of rows (do not show data for specific world regions)
Hide a changed table structure (so that legacy applications can continue to work)
As a view has itself some permissions attached to it, it is easier to GRANT permissions on the view as a whole, rather than defining cumbersome column-specific privileges on the underlying tables.
To activate views support on a server after an upgrade from a pre-5.0 version, the administrator has to execute the mysql_fix_privileges_tables script, as described in the MySQL manual.