House number

House numbering is the system of giving a unique number to each building in a street or area, with the intention of making it easier to locate a particular building. The house number is often part of a postal address. The term describes the number of any building (residential or commercial) with a letterbox, or even a vacant lot. House numbering also serves a public safety function; visible house numbers allow emergency services to locate properties more quickly, and both the International Fire Code and National Fire Protection Association fire codes require buildings to display address numbers that are legible and visible from the street.