The address for this web page is:
On to the next lesson!

Today's lesson explores URLs (Uniform Resource Locators), which allow you to locate documents and other resources on the World Wide Web. When you look in the "Address" line of your browser, you're seeing a URL!

a typical URL in the ADDRESS line

To specify URLs, you use the pathname conventions discussed on Day 17, but there are some other things you should know...



What is a URL? "URL" stands for "Uniform Resource Locator." (It "locates resources" for you on the web.) Here's an example that illustrates the usual parts of a URL:
  • a protocol identifier (the "http://" part)
    The most common protocol identifier is "http://", which points to a hypertext document accessible through the HyperText Transfer Protocol.
    Another common protocol identifier is "ftp://" (for a file accessible through the File Transfer Protocol).
  • the domain name (also called "host name")
    The domain name is the name of the server machine for the desired resource. The domain name in the example above is "" .
  • the pathname to the desired location in the server's file system
    The pathname in the example above is "sketchpad/sketchdemo.html" .

the "MAILTO" URL and more... (18b)

What is a "mailto" URL? The mailto protocol can be used in an anchor tag to automatically send an email message from within the browser. For example, the code

<A HREF=""> Send me an email! </A>

would produce this: (Try it out! Tell me how the course is going for you...)
Send me an email!

(The browser must be configured to support this tag, so it might not always work.)

What happens if there's a forward slash at the end of a URL? A forward slash (/) at the end of a URL means that you're pointing to a directory, not a file; i.e., you're asking to see the contents of the directory. This is a breach of privacy, so most servers are configured to to display a specific file (like "index.html" or "welcome.html" or "default.html") instead of the directory list. If the server doesn't find such a file, the directory contents may be displayed.

Printable version of Index Card 18a

Printable version of Index Card 18b



On to the next lesson!
© 2000 Carol J.V. Fisher    All Rights Reserved