Identifies the individual(s) to whom privileges are to be granted or from whom privileges are to be revoked.

It can appear in GRANT and REVOKE statements.

where user_identifier identifies the user to be granted/revoked privileges .

Defines whether to grant to or to revoke the privilege or privilege set from either a particular user, from a list of users, or from all users. If you specify the PUBLIC option, granting or revocation the specified privilege will automatically affect all present and future users.

By default, table owners hold all the privileges for their tables and should not grant themselves, or revoke from themselves, additional privileges on their tables.