The Philippines has a ZIP code system similar to many western countries; codes usually consist of four digits and are arranged geographically by city or town. The use of ZIP codes in the Philippines is not actually necessary or even obligatory.
The capital city of the Philippines, Manila, has by the far the largest number of ZIP codes in the country; some areas of the city encompass more than one ZIP code. Depending on an area's population density, a ZIP code can refer to different locales. For example, a ZIP code in Manila refers to a single city district, while outside the capital it generally refers to an entire city or town.