Understanding Row Identifiers(ROWID)

Each row in an Oracle database has a unique row identifier, or rowid. A ROWID is an 18-digit number that is represented as a base-64 number. ROWID is used internally by the Oracle database to access the row. ROWID is only used internally by the database. ROWID is known as a pseudo column. A rowid contains the physical address of a row in an Oracle database. You can view the rowid value by specifying the ROWID column. When you describe a table using the DESCRIBE command, ROWID doesn't appear.