ORA-65096: invalid common user or role name

SQL> create user garey identified by 123123;
create user garey identified by 123123
            *
ERROR at line 1:
ORA-65096: invalid common user or role name

SQL> show con_name
CON_NAME
------------------------------
CDB$ROOT
SQL> select pdb from v$services;
PDB
------------------------------
PDBORCL
CDB$ROOT
CDB$ROOT
CDB$ROOT
CDB$ROOT
SQL>


we need to decide whether create common user or a local user,
to create a common  user , the name must start with c##


SQL> create user c##garey identified by 123123;
User created.
SQL>


to create a user in orcl
SQL> alter session set container=PDBORCL;
Session altered.
SQL> create user garey identified by 123123;
User created.
SQL>