High Quality Content by WIKIPEDIA articles! In the Philippines, the Philippine ZIP code is used by the Philippine Postal Corporation (Philpost) to simplify the distribution of mail. While in function it is similar to the ZIP code used in the United States, its form and its usage is quite different. The use of ZIP codes in the Philippines is not mandatory, however it is highly recommended by Philpost that they be used. Also, unlike American ZIP codes, the Philippine code is a four-digit number representing two things: in Metro Manila, a barangay within a city or city district (as in the case for Manila), and outside Metro Manila, a town or city. Usually, more than one code is issued for areas within Metro Manila, and provincial areas are issued one code for every town and city.