User creation

Hi Experts,

I am new to postgresql, just wanted to know more about user creation.

I tried to create users using command [create user sam] without any option]
what are the default rights given to the user?

radius=> select * from pg_user;
usename | usesysid | usecreatedb | usesuper | usecatupd | userepl |
passwd | valuntil | useconfig
----------+----------+-------------+----------+-----------+---------+----------+----------+-----------
postgres | 10 | t | t | t | t |
******** | |
radius | 9479531 | f | t | t | t |
******** | |
sam | 9492031 | f | f | f | f |
******** | |

what doest 't' and 'f' denotes here?? just want to clarify...