High Quality Content by WIKIPEDIA articles! A persistent uniform resource locator (PURL) is a Uniform Resource Locator (URL) (i.e. location-based Uniform Resource Identifier or URI) that does not directly describe the location of the resource to be retrieved but instead describes an intermediate (more persistent) location which, when retrieved, results in redirection (e.g. via a 302 HTTP status code) to the current location of the final resource. PURLs are an interim measure ? while Uniform Resource Names (URNs) are being mainstreamed ? to solve the problem of transitory URIs in location-based URI schemes like HTTP. Persistence problems are caused by the practical impossibility of every user having their own domain name, and the inconvenience and money involved in re-registering domain names, that results in WWW authors putting their documents in rather arbitrary locations of questionable persistence (i.e. wherever they can get the WWW space). Existing official PURLs (on Purl.Org) will probably be mapped to a URN namespace at a later date. Technically the string resolution on PURL is like SEF URL resolution.