When an object is created, it is assigned an owner. The owner is normally the role that executed the creation statement. For most kinds of objects, the initial state is that only the owner (or a superuser) can do anything with the object. To allow other roles to use it, privileges must be granted.
   There are different kinds of privileges: SELECT,
   INSERT, UPDATE, DELETE,
   TRUNCATE, REFERENCES, TRIGGER,
   CREATE, CONNECT, TEMPORARY,
   EXECUTE, and USAGE.
   The privileges applicable to a particular
   object vary depending on the object's type (table, function, etc).
   For complete information on the different types of privileges
   supported by PostgreSQL, refer to the
   GRANT reference
   page.  The following sections and chapters will also show you how
   those privileges are used.
  
The right to modify or destroy an object is always the privilege of the owner only.
   An object can be assigned to a new owner with an ALTER
   command of the appropriate kind for the object, e.g., ALTER TABLE.  Superusers can always do
   this; ordinary roles can only do it if they are both the current owner
   of the object (or a member of the owning role) and a member of the new
   owning role.
  
   To assign privileges, the GRANT command is
   used. For example, if joe is an existing role, and
   accounts is an existing table, the privilege to
   update the table can be granted with:
GRANT UPDATE ON accounts TO joe;
   Writing ALL in place of a specific privilege grants all
   privileges that are relevant for the object type.
  
   The special “role” name PUBLIC can
   be used to grant a privilege to every role on the system.  Also,
   “group” roles can be set up to help manage privileges when
   there are many users of a database — for details see
   Chapter 21.
  
   To revoke a privilege, use the fittingly named
   REVOKE command:
REVOKE ALL ON accounts FROM PUBLIC;
   The special privileges of the object owner (i.e., the right to do
   DROP, GRANT, REVOKE, etc.)
   are always implicit in being the owner,
   and cannot be granted or revoked.  But the object owner can choose
   to revoke their own ordinary privileges, for example to make a
   table read-only for themselves as well as others.
  
Ordinarily, only the object's owner (or a superuser) can grant or revoke privileges on an object. However, it is possible to grant a privilege “with grant option”, which gives the recipient the right to grant it in turn to others. If the grant option is subsequently revoked then all who received the privilege from that recipient (directly or through a chain of grants) will lose the privilege. For details see the GRANT and REVOKE reference pages.