ROWID and UROWID Datatype in Oracle

ROWID Datatype
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•Each row stored in a table has an address. You can see a row address by querying ROWID pseudo column. Like,
SQL> select rowid from with_lob;
ROWID
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AAANp9AALAAADDPAAA

ROWIDs can be restricted Rowids which forms the format as block.row.file and can be Extended Rowids which forms the format as the data in the restricted rowid plus a data object number. The data object number can be found by querying from USER_OBJECTS, DBA_OBJECTS, and ALL_OBJECTS like
SQL> select DATA_OBJECT_ID from dba_objects;

UROWID Datatype
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The rows of some tables have addresses that are not physical or permanent or were not generated by Oracle Database. Like, the row addresses of index-organized tables are stored in index leaves, which can move.

Oracle uses universal rowids (urowids) to store the addresses of index-organized and foreign tables. Index-organized tables have logical urowids and foreign tables have foreign urowids.