Uniform Resource Locator

The World Wide Web uses Uniform Resource Locators (URLs) to specify the location of files on other servers. A URL includes the type of resource being accessed (e.g., http, gopher, ftp), the address of the server, and the location of the file.

The syntax is: scheme://host.domain[:port]/path/filename, Where scheme is:

• file: a file on the local system.
• http: a file on a World Wide Web server.
• gopher: a file on a Gopher server.
• telnet: a terminal window on an Unix server.
• ftp: an ftp session usually with a Unix server.

The URL "http://www.u3.org/hypertext/WWW/", is the address for The World Wide Web. Telnet creates a terminal window where one can login to a Unix server. Ftp is a file transfer protocol allows transfer or files to and from a remote host.

``Absolute'' links required not just the pathname of the file you wish to link to, but also the computer URL address where the file is located. In order to include a link to the NCSA's HTML primer in your document, you would use:

<a href = "http://www.ncsa.uiuc.edu/General/Internet/WWW/HTMLPrimer.html"> 
    NCSA's Beginner's Guide to HTML</a>

This would make the text ``NCSA's Beginner's Guide to HTML'' a hyperlink to NCSA's primer document.

''Relative'' links are to be used for files residing in the same computer as the requesting document. This is normally done for in-lined images or tables . Relative links allows for the document to migrate to other systems without having to reference to original files but the files that were moved also with it.