Explain ROWID in oracle

Explain ROWID in oracle.

A ROWID in oracle is a pseudo column that is not within the database. It is used to uniquely identify a row with a table.
The rowid values are used to locate necessary information to locate a row.

Example:
Below query selects address of all rows that contain data for students in department 20
SELECT ROWID, last_name
      FROM student
      WHERE department_id = 20;

Explain ROWID in oracle.

Each table in oracle has a pseudocolumn called ROWID. Oracle uses ROWID to store address of each rows of the table. Oracle uses ROWID to maintain indexes. Each key in an index is associated with a ROWID that points to the associated row's address for fast access.
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