Search notes:

users

Connecting to a database

A user must be authenticated by Oracle in order to be able to a database.

Error messages

Error messages that are related to failed attempts to log on the database include
Sometimes, its not even possible to connect to the database because of network problems or wrong configuration. In such a case, the user will receive one of the Oracle net error messages.

Oracle maintained users

Some Oracle maintained users are:
ANONYMOUS
APPQOSSYS
AUDSYS
DBSFWUSER
DBSNMP
DIP
GGSYS
GSMADMIN_INTERNAL Owner of the gsm administrative packages (catgwm.sql)
GSMCATUSER
GSMUSER
ORACLE_OCM
OUTLN
REMOTE_SCHEDULER_AGENT
SYS
SYS$UMF
SYSBACKUP
SYSDG
SYSKM
SYSRAC
SYSTEM
XDB
XS$NULL
This list was created with 
select
   username
from
   dba_users
where
   oracle_maintained = 'Y'
order by
   username

See also

dba_users, all_users, user_users, proxy_users.
A user owns zero, one or more objects.
Selecting the SQL Statements a user has parsed from v$sqlarea allows to get a rough (!) estimation of what a user was doing on a database.
dba_users_with_defpwd lists users that are still using their default passwords.
A user can be assigned a default tablespace.
Each user is assigned a profile which defines some database resource usage limits and constraints related to passwords.
Default roles of a user.
For each tablespace, a certain quota can be defined to the user.
Compiling a user's schema with dbms_utility.compile_schema.
Using the grant SQL statement to give users privileges.
As far as I can tell, there is not hist table for dropped users.
user$

Index