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A postal code is a series of letters and/or digits appended to a postal address for the purpose of sorting mail.
The vast majority of the world's postal services and/or countries have postal code systems. However, contrary to common misconception, not all do: The Republic of Ireland and Hong Kong, for example, do not have postal codes1, while New Zealand's post code system is only used for the presorting of mail in bulk, not for addressing individual items.
Postal services using postal codes mostly use their own respective different formats and placement for them. (Their service area is usually defined by national borders.)
In most English-speaking countries, the postal code goes after the name of the city or town, whereas in most continental European countries it goes before it and is often prefixed with a country code. This country code is similar to the one used on car license plates.
Although postal codes are usually assigned to geographical areas, sometimes this is not the case: special codes may be assigned to institutions with large volumes of post, such as government agencies and large commercial companies. One example is the French Cedex system.
Alphanumeric postal codes
Most postal codes are numeric. The few using alphanumeric postal code systems (with letters and digits) are:
Postal zone numbers
Before postal codes as described here were used, large cities were often divided into postal zones (or postal districts), usually numbered from 1 up within each city. The newer postal code systems often incorporate the old zone numbers, as with London postal district numbers, for example. Dublin, Ireland still uses postal district numbers, as postal codes are not used in the country at all. (An Post relies on OCR analysis of the entire address instead.) In New Zealand, Auckland, Wellington and Christchurch were also subdivided into postal zones, but these have fallen into disuse.
See also
External links
Footnote
1 Irish postal district/zone numbers (see above) are used for Dublin only. Confusingly, these postal zone numbers are sometimes also called postal codes—which could be seen as technically incorrect.
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