There are now may geocoding web services out there, like Google geocoder, Yahoo geocoder, geocoder.us (only for US address), Microsoft MapPoint, GeoNames and MediaWiki.
Normally you may access this web services API directly with HTTP REST request, and get a response in common formats like xml, json, kml.
For example you may geocode with the Google geocoder an address like this one: “1071 5th Avenue, New York, NY” with a request like this one:
In this case we are querying the Google geocoder web service to get a response in json via the output parameter in the query string. This is the json response we get back from the web service:
