URL

URL is an abbreviation for Uniform Resource Locator. It was previously known as the Universal Resource Locator and is a type of Uniform Resource Identifier. The URL is a unique address or file path that represents the location of a file on the internet and also specifies the method to retrieve the resource from the location. URL is often confused with URI, which is a unique identifier of a resource on the internet. A URL is a type of URI like a URN (Uniform Resource Name) which is a unique name of a resource.

Every website on the internet has a unique URL, which can be entered into the address bar of a web browser to access and view it. Any other file or resource such as an image file, web (HTML) page other than the home page, Java applet and even a programs imbedded inside a site, such as a Common Gateway Interface (CGI) application, can also be accessed using a URL.

The URL consists of a protocol that tells the web browser how to retrieve the file or a resource; a domain name which identifies a specific computer on the Internet; and a pathname, a hierarchical description, which specifies the location of the particular file on the computer. A computer referred here can also be called a web server which stores web pages and files associated with them and provide them to clients (web browsers) when a request is made in the form of accessing a URL.

Syntax

A typical URL can be of the following manner:

http://www.abcd.org/def/def1234.txt

The first part specifies the scheme, which is http, separated from the rest by a colon. The rest of the part of URL follows the colon in a format specific to the scheme. The Internet mainly uses the HTTP (Hypertext Transfer Protocol) scheme to transfer HTML pages on the web. Other such protocols are ftp, gopher, mailto, wais, and so on.

The second part, www.abcd.com specifies the unique computer name. This name is a hierarchy of domains which descend from right to left separated by a dot. The rightmost domain, or as technically called, label is the top level domains which can be gTLDs - .com, .org, .net, etc; or ccTLDs - .us, .fr, .de, etc.

Next is the location of a resource as given in the example a text file, def1234.txt, to be accessed on that computer which is given by a pathname "/def/def1234.txt".

History

The URL was first created in the year 1994 by Tim Berners-Lee and the URI working group of the Internet Engineering Task Force. Berners Lee had earlier used dots to separate the parts of the domain name inside URLs but he then regretted it and wished that he had used slashes throughout. For instance, he proposed that it is better to use http:com/sample/www/path/to/name instead of http://www.sample.com/path/to/name . Twenty years after creating the URL, Tim Berners-Lee in an interview to Times newspaper also held a light apology for using the two forward slashes (//) before the domain name.

Types of URL

URL is basically of two types, Absolute and Relative. The Absolute URL is a URL, which is independent of other elements and points directly to the exact file location For instance,"mywebsite.com/images/homepage.jpg" is an absolute URL, which specifies that the image file homepage.jpg is located in the images directory, under the mywebsite domain.

A Relative URL is a type of URL, which is depended on other elements and point to a directory or file in relation to the present directory or file. A good example of this type of URL would be "../image/homepage.jpg". In this, the first two periods (..) direct the server to move up one directory (the root directory), then enter images directory and then point to the homepage.jpg file. The main benefit of Relative URL is it helps the web masters to make changes in the directory as and when they want without rewriting the entire path again and again.

SEO benefits

There is a latest trend in the search engines, which says that URLs when shortened can really play a major role in Search Engine Optimization (SEO) of a web site. Many SEO experts advice that a URL of the form: www.yourwebsite.com/category/subcategory leads to better search engine rankings. . Google, a leading search engine has also developed URL shortener, which helps to convert longer URLs into short ones. This has been created in the view that, with shorter URLs people can easily share the links of their web site on the popular social networking sites such as Twitter and Facebook and in turn can get huge back-links and increase traffic to their web site.

Hypertext Transfer Protocol

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