Geocoding is a way of georeferencing data by using a GIS data layer that has locational information. For example, a geographic dataset showing street information which includes the street name and the beginning and ending address tied to each street segment could be used to geocode a database with addresses. The process creates a derivative GIS dataset in which geographic coordinates are applied to each record in the original database based on locational information applied from a secondary dataset such as a streets layer or a parcels database.
What can be geocoded? A variety of address formats can be geocoded, depending on the type of GIS data you are using. Most commonly use is to geocode a database of addresses (street number and name). Points of interests (such as landmarks or common places), cities, and ZIP codes are other address-like records that can be geocoded.
Reverese geocoding is the process of converting geographic coordinates to the nearest address.
Listed here are further tutorials to learning about geocoding and resources for online for you to geocode with.
A basic overview of what geocoding is with a step-by-step example using ArcView 3.x. Find out how to map out your addressed databases.
Free service put together by Phillip Holmstrand using Google’s geocoding API. It lets you batch geocode addresses not just one at a time. Up to 3,000 records per day per IP address. The process returns a Google map of all geocoded locations and the results can be downloaded as a KML file.
Google’s Geocoding API
Google offers an API for converting addresses to geographic coordinates and for reverse geocoding. The API has a query limit of 2,500 geolocation requests per day.
GeoLocator is a tool designed for easy geocoding and geotagging for Wikipedia articles. Users can enter an address or drop the icon to the area of interest and the page will return Wiki geotags.