how to setup default privileges

Hello,

When an object is created by the default user "user1", I ran:
\dp+ tableName , and got:


   Schema    | Name | Type  | Access privileges
-------------+------+-------+-------------------
 schemaName | t1   | table |                       --- step 0

The Access privileges is blank. However, I am able to insert, update,
delete , etc on the newly created t1.

Could somebody tell me that what are the default privileges for table t1
please? Does it equal to
grant all on t1 to "user1", please?


After running "revoke all on t1 from user1", how to reset the table
privileges back to step 0 please?


Thanks a lot,
Emi