Geocoding (geographically enabling unit records) is defined as the process of finding associated geographic coordinates (expressed in latitude and longitude) from other geographic data for the statistical units, such as street addresses or postal codes. (Geocoding is a way to ensure that the data “knows” where it is.)
In other words, geocoding involves taking location information for these statistical units (such as address) and linking this information to a location coordinate (i.e., x,y,z coordinates) and/or a small geographic area. The geocodes (the location coordinates and geographic areas codes) obtained from this process can be stored directly on the statistical unit record or linked in some way to the record. There is a common misunderstanding between geocoding and georeferencing, so it is important to emphasize that while they are related, they are quite different. Georeferencing is often done, for example, with raster images. Georeferencing is the process of referencing data against a known geospatial coordinate system by matching to known points of reference in the coordinate system so that the data can be analyzed, viewed, and queried with other geographic data.
In the GIS industry, geocoding is synonymous with address matching, which is the process of assigning map coordinate locations to addresses in a database.30 A GIS is capable of doing this by comparing the elements of an address or a table of addresses with the address attributes of a reference dataset—the GIS data layer used as the geographic reference layer (e.g., a city’s street centerlines layer)—to find a match (i.e., to determine whether particular address falls within an address range associated with a feature in the reference).
But the concept of geocoding goes beyond address matching. It covers a continuum of spatial scales: from individual housing units to EA levels, up to higher administrative or national levels. The use of GPS, directly capturing precise data at the level of point locations (latitude and longitude coordinates), allows the coding of centroids, building corners, or building point-of-entry coordinates for a unit such as a block of land, building, or dwelling.
Excerpt From: Amor Laaribi. “GIS and the 2020 Census.” iBooks.