Oracle Date Conversion function - TO_DATE()

TO_DATE in Oracle pl/sql is to convert char data type to a value of DATE data type.

TO_DATE( String, format, nls_param )
String : is the string to convert to date
format : is the format that will be used to convert string to a date.
nls_param : is the nls_languageused to convert string to a date.

Examples:
SQL> select to_date('APR/03/2009' ,'MON-DD-YYYY HH24:MI:SS') DATE from dual;
SQL> select to_date('20080312','YYYYMMDD') from dual;
SQL> select to_date('20080312','YYYYDDMM') from dual;
SQL> select to_date('2006/11/14 18', 'yyyy/mm/dd hh24') from dual;