System Tables Views Oracle PLSQL

SQL>
SQL>
SQL> describe user_objects
 Name                                                                                                      Null?    Type
 ----------------------------------------------------------------------------------------------------------------- -------- ----------------------------------------------------------------------------
 OBJECT_NAME                                                                                                        VARCHAR2(128)
 SUBOBJECT_NAME                                                                                                     VARCHAR2(30)
 OBJECT_ID                                                                                                          NUMBER
 DATA_OBJECT_ID                                                                                                     NUMBER
 OBJECT_TYPE                                                                                                        VARCHAR2(19)
 CREATED                                                                                                            DATE
 LAST_DDL_TIME                                                                                                      DATE
 TIMESTAMP                                                                                                          VARCHAR2(19)
 STATUS                                                                                                             VARCHAR2(7)
 TEMPORARY                                                                                                          VARCHAR2(1)
 GENERATED                                                                                                          VARCHAR2(1)
 SECONDARY                                                                                                          VARCHAR2(1)
SQL>
SQL> select object_type, object_name
  2  from user_objects
  3  where rownum < 50
  4  order by object_type, object_name;
OBJECT_TYPE         OBJECT_NAME
------------------- --------------------------------------------------------------------------------------------------------------------------------
CLUSTER             C_COBJ#
CLUSTER             C_FILE#_BLOCK#
CLUSTER             C_OBJ#
CLUSTER             C_TS#
CLUSTER             C_USER#
INDEX               I_CCOL1
INDEX               I_CDEF1
INDEX               I_CDEF2
INDEX               I_CDEF4
INDEX               I_COBJ#
INDEX               I_COL2
OBJECT_TYPE         OBJECT_NAME
------------------- --------------------------------------------------------------------------------------------------------------------------------
INDEX               I_COL3
INDEX               I_CON1
INDEX               I_CON2
INDEX               I_FILE#_BLOCK#
INDEX               I_FILE1
INDEX               I_FILE2
INDEX               I_IND1
INDEX               I_OBJ#
INDEX               I_OBJ1
INDEX               I_OBJ2
INDEX               I_OBJ3
OBJECT_TYPE         OBJECT_NAME
------------------- --------------------------------------------------------------------------------------------------------------------------------
INDEX               I_PROXY_DATA$
INDEX               I_PROXY_ROLE_DATA$_1
INDEX               I_TAB1
INDEX               I_TS#
INDEX               I_TS1
INDEX               I_UNDO1
INDEX               I_UNDO2
INDEX               I_USER1
TABLE               BOOTSTRAP$
TABLE               CCOL$
TABLE               CDEF$
OBJECT_TYPE         OBJECT_NAME
------------------- --------------------------------------------------------------------------------------------------------------------------------
TABLE               CLU$
TABLE               COL$
TABLE               CON$
TABLE               FET$
TABLE               FILE$
TABLE               ICOL$
TABLE               IND$
TABLE               OBJ$
TABLE               PROXY_DATA$
TABLE               PROXY_ROLE_DATA$
TABLE               SEG$
OBJECT_TYPE         OBJECT_NAME
------------------- --------------------------------------------------------------------------------------------------------------------------------
TABLE               TAB$
TABLE               TS$
TABLE               UET$
TABLE               UNDO$
TABLE               USER$
49 rows selected.
SQL>
SQL> column object_name format a30;
SQL>
SQL>