URIs classification

URIs can be classified as either locations (URLs) or names (URNs).

Uniform Resource Locator (URL)
A Uniform Resource Locator (URL) describes how to locate or reach a resource. For example, an Web page is accessible through a URL. When given an URL such as http://www.componize.com/images/logo.gif, one should have enough information to retrieve the resource, using a specific protocol (HTTP), host ( www.componize.com) and remote path ( /images/logo.gif).
Uniform Resource Name (URN)
A Uniform Resource Name (URN) is generally a unique identifier, with a naming scheme depending on the context. For example the ISBN of a given book is a URN. urn:isbn:0-486-27557-4may be used as the identifier for a specific edition of Romeo and Juliet. mailto:support@componize.commay also be considered a URN.The naming scheme for URNs is specific to its context. However, as a URI, an URN has to apply to a set of rules, such as the encoding of special characters.