The Oracle COMMIT statement ends then current transaction within RDBMS and makes all changes visible to other users.

A COMMIT statement also erases all existing savepoints and releases transaction locks.

The general format is:

COMMIT [ WORK ] [ COMMENT clause ] [ WRITE clause ] [ FORCE clause ];

Alternatively, a ROLLBACK statement can be issued, which undoes all the work performed.

Oracle Database issues an implicit COMMIT before and after any data definition language (DDL) statement.

Oracle recommends that you explicitly end every transaction in your application programs with a COMMIT or ROLLBACK statement before disconnecting from Oracle Database.
If you do not explicitly commit the transaction and the program terminates abnormally, then the last uncommitted transaction is automatically rolled back.

Example 1:

INSERT INTO country VALUES (34, 'Spain');

Example 2:
DELETE FROM country WHERE countrycode=34;
COMMIT COMMENT 'Comment for the transaction';