URL design guidelines definitions

On this page:


Canonical URL

Standard single version of a URL for a single web page, when there may be more than one way to represent the URL (or address) of a page. The URL that is set as the only URL to be able to serve that particular web page.

Clean URL

URLs that are short, understandable, have some permanence and are not tied to technical details. Consistent with other URLs in the same site in terms of hierarchy and in terms of action. A single location for a single resource.


Dirty URLs

URLs which are meaningless, complex, and hard-to-read. These URLs do not promote usability as they are difficult to remember, repeat or type. 'Dirty' URLs can also pose a security risk depending on the type of information contained within them.


HTTP status code

HTTP status codes are standard response codes returned by web servers in response to HTTP requests. For example: a well known HTTP status is 404, this status is sent by a server when the requested resource cannot be located (or in a few other edge cases). Another common HTTP status is 200, this status is sent by the server when a document is found successfully, and is usually returned bundled with the requested document.


Persistent URL

A URL designed to remain stable indefinitely.
Alternate meaning: A URL that does not directly describe the location of the resource to be retrieved, but instead describes an intermediate location which, when retrieved, results in redirection to the current location of the final resource.


Query String

The part of a URL that conveys parametric data to the server. Comprises a character string beginning with a question mark (?), composed of name-value pairs of input, separated by ampersands (&). For example ?name=john&rank=2.


Session ID

A session ID is a unique number that a Web site's server assigns a specific user for the duration of that user's visit. The session ID can be stored as a cookie, form field, or URL parameter. Some Web servers generate session IDs by incrementing static numbers or by the use the date and time of the visit along with other variables defined by the server administrator.



Uniform Resource Identifier. Often used synonymously with URL. In this document, URI has been used to refer to the path to a resource inside of a domain. For the URL http://example.com/path/to/resource.html, the following would be referred to as a URI /path/to/resource.html


Uniform Resource Locator. A formatted string that serves as an identifier for a resource on the Internet. A URL usually consists of the access protocol (http), the domain name and optionally the path to a file or resource residing on that server. URLs are a subset of the larger URI set.