postcode

A postcode is a code used by postal services to identify a geographic area for the purpose of sorting and delivering mail. In many countries, postcodes are also used for navigation, emergency services, marketing, and geographic analysis, helping align addresses with regional statistics, service levels, and planning.

Formats and conventions vary by country. The United States uses numeric ZIP codes, typically five digits, often extended with ZIP+4 for more precise routing. The United Kingdom uses alphanumeric postcodes that encode area, district, sector, and delivery point. Canada employs alphanumeric postal codes in the format A1A 1A1. Germany uses five-digit numeric codes, while India uses six-digit PINs. These systems are designed to facilitate automated sorting and efficient routing.

Postcodes originated in the mid-20th century as part of national efforts to modernize mail delivery and improve automation. The United Kingdom began pilot testing postcodes in 1959, with nationwide adoption over the following years. The United States introduced the ZIP code system in 1963 to enhance sorting efficiency, and Canada began widespread use in the 1970s.

Current uses extend beyond mail handling. Postcodes support address validation in e-commerce and human services, enable geocoding for mapping and urban planning, and assist in demographic analysis and resource allocation. They can be updated to reflect boundary changes and urban development, and in some contexts raise privacy considerations when linked to location data.