The Address parser webservice divides a single address string into its individual component parts : house number, street type (bd, street, ..), street name, unit (apt, batiment, ...), zipcode, state, country, city, ... via a REST interface.
It uses (free) data from OpenstreetMap that are imported into a local database.
You can see an example of use bellow. You can find documentation on how to use the XML API of the webservice and see how to download and install Gisgraphy.
The address parser takes an address as input as it could be writen on an envelopp. If you want to search for a city or a street that is not a real address, use the géocoder. If you search for a place, use the full text engine