exception is used to handle runtime error in plsql. there are 3 types of exceptions 1 pre-defined exceptions some of this NO_DATA_FOUND, ZERO_DIVIDE, TOO_MANY_ROWS. 2 USER DEFINED EXCEPTIONS - we create our own expception and raised whenever neccesary explicitly. 3. unnamed exception;- method we are creating our own exception name and they associates this exception name with appropriate error number by using EXCEPTION_INIT