URLs -- Referencing An Internet Resource

• To get something, your browser needs to know:
  • What protocol to use to get it
  • Which computer it is found on
  • Where it is located on the specified computer.
• This information is all contained in a URL.
• A URL is a simple text string containing all the information needed to find a resource.

An Example URL (Talk Home Page)

 http://www.utoronto.ca/ian/talks/mm97-a/intro.html

1. http:// -- How to get it (the protocol)
2. www.utoronto.ca --Which computer (the domain name)
3. /ian/talks/mm97-a/intro.html -- Where on the computer

Some More Examples

• http://www.utoronto.ca/webdocs/webinfo.html
• ftp://ftp.netscape.com
• telnet://library.utoronto.ca

The server either sends a copy of the requested resource, or it sends back an error message ("404 Not Found!"). When the copy arrives at your machine, the browser displays it for you.

Placing URLs in HTML Document

HTML has a way of including these hypertext links right in the docoument. Thus you only need to type in those horrible URLs once -- thereafter, all you need do is click on the link.