House numbers are numbers or letters that are used to identify houses or other buildings. They are often used to help locate a specific house or building, or to help with the delivery of mail or other deliveries. House numbers are often placed on the door or on a sign near the front door of a house or building, so that they can be easily seen from the street. In some areas, it is required to have house numbers, while in other areas their use is voluntary. House numbers are often used in conjunction with street names to indicate the specific address of a house or building.