scott@9i > select table_name,tablespace_name from user_tables where table_name='EMP';
TABLE_NAME TABLESPACE_NAME
------------------------------ ------------------------------
EMP USERS
scott@9i > column file_name format a70
scott@9i > select file_name from dba_data_files where tablespace_name='USERS';
FILE_NAME
----------------------------------------------------------------------
/u01/app/oracle/oradata/mutation/users01.dbf
Start with the Oracle concepts manual.
All data are stored in datafiles (in hard disk). Ignore the .dbf extension. It can be anything.
These physical datafiles are grouped together by a logical tablespace.