Geocode Service uses Geocoder.us to replace a selected street address with its approximate latitude and longitude.

Geocoding works by interpolating the position of an address between the endpoints of a street segment of known location and address range. The Census Bureau maintains a public dataset commonly used for this purpose. Geocoding accuracy is limited by the accuracy of the reference dataset as well by assumptions about the regular distribution of addresses along a street. For this reason it works most reliably in urban environments where successive addresses are physically adjacent and uniformly distributed along the length of the street.