EXTRACT

The Oracle and PL/SQL EXTRACT function extracts a value from a date or interval value.

EXTRACT (
{ YEAR | MONTH | DAY | HOUR | MINUTE | SECOND }
| { TIMEZONE_HOUR | TIMEZONE_MINUTE }
| { TIMEZONE_REGION | TIMEZONE_ABBR }
FROM { date|interval } )

Example 1:

SELECT EXTRACT(YEAR FROM TO_DATE('05/06/2015','DD/MM/YYYY')) FROM DUAL;
2015