housenumber

A housenumber, or house number, is a numeric or alphanumeric identifier assigned to a building within a street or road. It forms a key part of a postal address and is used to locate a building for mail delivery, navigation, emergency services, and property records.

Numbers are usually displayed on the exterior of the building and are paired with the street name. A single street may have many points of access, and some addresses include additional subdivisions such as unit or apartment numbers, which are not part of the house number itself.

Numbering schemes vary by country and local authority. In many places, even numbers appear on one side of the street and odd numbers on the other; numbers often increase as one moves along the street. Some systems permit alphanumeric house numbers (for example, 12A, 12B) to accommodate subdivisions or former buildings. In some countries, the building name can precede or replace the house number in common usage.

Municipal governments or postal authorities usually assign and maintain house numbers and publish street address lists. Renaming or re-numbering streets, new infill development, or changes to street layouts can lead to updates in numbering.

In the digital age, house numbers are linked to geocoding databases and mapping services, enabling search, routing, and emergency dispatch, and may be tied to postal codes or geographic coordinates.