- Uniform Resource Locators are defined in RFC 1738, which was adopted in 1994. RFC stands for Request For Comment, which is how new Internet technology becomes standardized. Proper URLs follow RFC 1738 guidelines. As the name implies, they are used to find and present a variety of resources to the requester.
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URLs have two main parts: the scheme and the scheme-specific part. These parts are separated by a colon ( : ) in the URL string. So for a Web address, the scheme is http and the scheme-specific part is the domain name.
The most common scheme, of course, is http. But there are many others, some of which are still common. Here are all the RFC specified schemes:
ftp: File Transfer Protocol
http: Hypertext Transfer Protocol
gopher: The Gopher protocol
mailto: Electronic mail address
news: USENET news
nntp: USENET news using NNTP access
telnet: Reference to interactive sessions
wais: Wide Area Information Servers
file: Host-specific file names
prospero: Prospero directory service -
The most used and recognizable URLs are those we use to navigate through the Internet. The protocol defined is http (Hypertext Transfer Protocol). Here is how it appears schematically:
http://<host>:<port>/<path>?<searchpart>
The only required parts of the above statement are the protocol, http, the colon and the <host> definitions. The other components are optional. Using this string, the resource you are looking for appears in your browser if everything is entered correctly and is valid. - We often do not have to know the exact URL when calling up the desired resource. URLs are presented to us as links, or hyperlinks, which are more readable. A link is simply a mask over the URL that makes more sense to the reader of a Web page. For example, in Resources below, you see the hyperlinked text "URL RFC" instead of "http://www.isi.edu/in-notes/rfc1738.txt." Rather than typing the exact URL into your browser, you click the link and it renders the URL for you. Most Web browsers will render a full URL into a link that automatically directs you to that page so you do not have to copy and paste or type the address into the browser's address bar.
- The benefits of URLs are seen every day by millions of Internet users all over the world. The simple construction and standardization of the URL is what makes Web browsing, blogging, email, chat and online business possible. The next time you look at a typical URL, you can appreciate all that it allows you to accomplish.











