Web addresses are recorded in a Uniform Resource Locator (URL),
a logical address of a web page that can always used to dynamically
retrieve
the current physical copy over the Internet.
The key advantage of the Uniform Resource Locator's
(URL) is its universality, since the address is the same no matter where
in the world
it
is
used.
This is why Tim Berners-Lee proposed in RFC
1630, Universal Resource Identifiers in WWW, that it be called a Universal Resource
Identifier (URI)
to suggest his vision of a network where anything could be linked to anything.
However,
he experienced philosophical
resistance to this idea of universality from the IETF
team working on the web standards, and so the address became named the now
familiar Uniform Resource Locator.
The word URL can be
pronounced either "U-R-L" or "earl". The URL of the current
page is usually shown at the top of your web browser, and should be something
like "http://www.livinginternet.com/". Most web sites are accessible
without
a "www" prefix, originally used to differentiate web servers from other
servers such as FTP sites, but now generally redundant. The general format of
a URL is like a branch of a
tree, and can include a user, password, and port host:
service: // <user> : <password>
@ <host> : <port> /
<folder-1> / ... / <folder-n> / <page.html>
There
are several different standard URL formats, listed below in rough order of
frequency
of use:
| Web
| http://www.twenty.net/smith/index.html
|
| FTP
| ftp://ftp.twenty.net/pub/recipes/icecream.txt
|
| Email
| mailto:user@host
|
| Usenet
| news://user:password@host:port/newsgroup
|
| Telnet
| telnet://user:password@host:port/
|
| Gopher
| gopher://twenty.net/00pub/main1.txt
|
| File
| file://D|/Web
Site/recipes/chickensoup.html |
|
WAIS |
wais://twenty.net/pub/main1.txt
|
| Application
| Invoke
a local program; for example, start RealPlayer:
pnm://twenty.net/music/start.rm
|
| Prospero
| prospero://twenty.net/pub/main2.txt
- Historical Archie protocol. |
A URL
looks like a computer file path name, where the domain name is the computer, the
folders are the file path, and the web page is the file. This is how web servers
match URLs to files on their hard drive. However, URLs are separated by "/"
and for some reason file path names are separated with "\", leading to the following reaction from most users:
:-(
:-/ :-o :-&
:-@
You can select, copy, and paste a URL like
any other text after loading a page if you have the URL
displayed. On most web pages you can copy the URL with two commands: <tab>
or <shift><tab> to highlight the URL, and <ctrl>-c to copy.
Just for the fun of it, some people have gone to the effort of creating
URL's that are palindromes - read the same forward and backwards. Jonathan
Bowen had the first recorded URL palindrome at:
http://www.rdg.ac.uk/~sssbownj/jnwobsss~/ku.ca.gdr.www//:ptth/
Resources. Request For Comments documents on URL's are listed below:
- RFC 1738; Uniform
Resource Locators (URL); T. Berners-Lee, L. Masinter; December 1994.
- RFC 1808; Relative
Uniform Resource Locators; R. Fielding; June 1995.
- RFC
2396; Uniform Resource Identifiers (URI): Generic Syntax; T. Berners-Lee,
R. Fielding, L. Masinter; August 1998.
The following sites provide
more information on URL's:
