Postal codes are a specific set of numbers and letters (although sometimes they can include other characters) that help postal services identify a geographic area for efficient sorting and delivery of mail. They are used worldwide and vary in format and length depending on the country or region. Postal codes are much more than just a way of getting direct mail, they also have many real-life uses such as geocoding, address validation, and even helping with identity verifications.
The first postal codes were created for the city of London in 1857 and later expanded to cover other large cities. Postal code systems grew to encompass smaller areas such as neighborhoods, districts, communities, towns, and cities before extending to state-wide or nationwide postal codes. The United Nations-administered Universal Postal Union (UPU) maintains standards for postal code systems around the world.
In the United States, a ZIP code is a five-digit number that identifies a geographic area for the purpose of sorting and delivery of mail. The first three digits indicate the district or regional postal center, the next two digits indicate the geographic area of a town or city, and the last four digits identify a box section or number, portion of a rural route, building, or other specific delivery location.
In some countries, such as the UK, a postal code is related to an individual land lot and therefore the same code may be associated with multiple properties. In other cases such as in parks or large houses, a postal code is based on the entrance to the property and often consists of one or two letter sections.