Exception is the error handling part of PL/SQL block. The types are Predefined and user defined. Some of Predefined exceptions are.

CURSOR_ALREADY_OPEN

DUP_VAL_ON_INDEX

NO_DATA_FOUND

TOO_MANY_ROWS

INVALID_CURSOR

INVALID_NUMBER

LOGON_DENIED

NOT_LOGGED_ON

PROGRAM-ERROR

STORAGE_ERROR

TIMEOUT_ON_RESOURCE

VALUE_ERROR

ZERO_DIVIDE

OTHERS.

exception is an identifier and error handling part of pl/sql types := 1)predifined

2) user defined.