Yahoo! GeoPlanet is a Web service, accessible at http://where.yahooapis.com/v1[parameters]
Requests to GeoPlanet are sent as HTTP GET messages, using a URI (Uniform Resource Identifier) to indicate what resource or collection is desired, and HTTP headers to provide context for the request. A GeoPlanet URI is composed of a resource/collection name, an optional filter description, optional matrix parameters, and optional and required query parameters. A GeoPlanet request may have several headers describing the desired content type and language for the response