Clean URLs
Encyclopedia
Clean URLs, REST
ful URLs or user-friendly URLs are purely structural URL
s that do not contain a query string
and instead contain only the path of the resource (after the scheme [e.g. http] and the authority [e.g. example.org]). This is often done for aesthetic, usability, or search engine optimization
(SEO) purposes. Other reasons for designing a clean URL structure for a website
or web service
include ensuring that individual resources
remain under the same URL for years, which makes the World Wide Web
a more stable and useful system, and to make them memorable, logical, easy to type, human-centric, and long-lived.
But there can also be different levels of cleanness. It is usually recommended for usability and SEO purposes to make URLs descriptive; so when planning the structure of clean URLs, webmasters often take this opportunity to include relevant keywords in the URL and remove irrelevant words from it. So common words like "the", "and", "an", "a", etc. are often stripped out to further trim down the URL while descriptive keywords are added to increase user-friendliness and improve search engine ranking. This includes replacing hard-to-remember numerical IDs
with the name of the resource it refers to. And, because not all resources have URL-friendly names due to the character set restrictions on web URLs or length, it is common practice to generate a slug
that is truncated to a certain length and has any invalid characters replaced with human-readable characters. This also eliminates ugly and hard to remember URL-encoded
strings (e.g. Peanut%20M%26Ms becomes Peanut_MMs).
Similarly, it is common practice to replace cryptic variable names and parameters with friendly names or to simply do away with them altogether. Shorter URLs that don't contain any esoteric abbreviations or complex syntax that is alien to the average user are less intimidating and contribute to overall usability.
Another aspect of clean URLs is that they do not contain implementation details of the underlying web application. For example, many URLs include the filename of a server-side script
, such as "example.php", "example.asp" or "cgi-bin". Such details are irrelevant to the user and do not serve to identify the content, and make it harder to change the implementation of the server at a later date. For example, if a script at "example.php" is rewritten in Python
, the URL will have to change, or rewrite rule
s will need to be used to allow the old URL to redirect to the new one.
Representational State Transfer
Representational state transfer is a style of software architecture for distributed hypermedia systems such as the World Wide Web. The term representational state transfer was introduced and defined in 2000 by Roy Fielding in his doctoral dissertation...
ful URLs or user-friendly URLs are purely structural URL
Uniform Resource Locator
In computing, a uniform resource locator or universal resource locator is a specific character string that constitutes a reference to an Internet resource....
s that do not contain a query string
Query string
In World Wide Web, a query string is the part of a Uniform Resource Locator that contains data to be passed to web applications such as CGI programs....
and instead contain only the path of the resource (after the scheme [e.g. http] and the authority [e.g. example.org]). This is often done for aesthetic, usability, or search engine optimization
Search engine optimization
Search engine optimization is the process of improving the visibility of a website or a web page in search engines via the "natural" or un-paid search results...
(SEO) purposes. Other reasons for designing a clean URL structure for a website
Website
A website, also written as Web site, web site, or simply site, is a collection of related web pages containing images, videos or other digital assets. A website is hosted on at least one web server, accessible via a network such as the Internet or a private local area network through an Internet...
or web service
Web service
A Web service is a method of communication between two electronic devices over the web.The W3C defines a "Web service" as "a software system designed to support interoperable machine-to-machine interaction over a network". It has an interface described in a machine-processable format...
include ensuring that individual resources
Resource (Web)
The concept of resource is primitive in the Web architecture, and is used in the definition of its fundamental elements. The term was first introduced to refer to targets of Uniform Resource Locators , but its definition has been further extended to include the referent of any Uniform Resource...
remain under the same URL for years, which makes the World Wide Web
World Wide Web
The World Wide Web is a system of interlinked hypertext documents accessed via the Internet...
a more stable and useful system, and to make them memorable, logical, easy to type, human-centric, and long-lived.
Examples
Examples of "clean" versus "unclean" URLs follow:Reasoning and common practices
The most often cited reasons for using clean URLs is for search engine optimization, but clean URLs can also greatly improve usability and accessibility. Removing unnecessary parts, simplifies URLs and makes them easier to type and remember.But there can also be different levels of cleanness. It is usually recommended for usability and SEO purposes to make URLs descriptive; so when planning the structure of clean URLs, webmasters often take this opportunity to include relevant keywords in the URL and remove irrelevant words from it. So common words like "the", "and", "an", "a", etc. are often stripped out to further trim down the URL while descriptive keywords are added to increase user-friendliness and improve search engine ranking. This includes replacing hard-to-remember numerical IDs
Surrogate key
A surrogate key in a database is a unique identifier for either an entity in the modeled world or an object in the database. The surrogate key is not derived from application data.- Definition :There are at least two definitions of a surrogate:...
with the name of the resource it refers to. And, because not all resources have URL-friendly names due to the character set restrictions on web URLs or length, it is common practice to generate a slug
Slug (web publishing)
A slug is the part of a URL which identifies a page using human-readable keywords , for example "Slug_", rather than an opaque identifier such as the ID number of the content within the database...
that is truncated to a certain length and has any invalid characters replaced with human-readable characters. This also eliminates ugly and hard to remember URL-encoded
Percent-encoding
Percent-encoding, also known as URL encoding, is a mechanism for encoding information in a Uniform Resource Identifier under certain circumstances. Although it is known as URL encoding it is, in fact, used more generally within the main Uniform Resource Identifier set, which includes both Uniform...
strings (e.g. Peanut%20M%26Ms becomes Peanut_MMs).
Similarly, it is common practice to replace cryptic variable names and parameters with friendly names or to simply do away with them altogether. Shorter URLs that don't contain any esoteric abbreviations or complex syntax that is alien to the average user are less intimidating and contribute to overall usability.
Another aspect of clean URLs is that they do not contain implementation details of the underlying web application. For example, many URLs include the filename of a server-side script
Server-side scripting
Server-side scripting is a web server technology in which a user's request is verified by running a script directly on the web server to generate dynamic web pages. It is usually used to provide interactive web sites that interface to databases or other data stores. This is different from...
, such as "example.php", "example.asp" or "cgi-bin". Such details are irrelevant to the user and do not serve to identify the content, and make it harder to change the implementation of the server at a later date. For example, if a script at "example.php" is rewritten in Python
Python (programming language)
Python is a general-purpose, high-level programming language whose design philosophy emphasizes code readability. Python claims to "[combine] remarkable power with very clear syntax", and its standard library is large and comprehensive...
, the URL will have to change, or rewrite rule
Rewrite rule
In linguistics, a rewrite rule for natural language in generative grammar is a rule of the form A → X where A is a syntactic category label, such as noun phrase or sentence, and X is a sequence of such labels and/or morphemes, expressing the fact that A can be replaced by X in generating the...
s will need to be used to allow the old URL to redirect to the new one.