URLs- Pointers to the Internet

Now it is time to include links to information available on the Internet using the World Wide Web's addressing scheme for writing HTML anchor tags.

Objectives

After this lesson you will be able to:

Identify the function of Uniform Resource Locators (URLs).
Recognize the structure of a URL

Lesson

Note: For this lesson, you will not need your HTML text file.

What is a URL?

The Uniform Resource Locator (URL) is what the WWW uses to find the location of files and documents from computers on the Internet. On your WWW browser screen, the URL for this document is displayed in the upper part of the Web browser window. The URL includes:

an identifier for the type of Internet server;
an Internet address; and
a file path to the particular item of interest.

The URL is what you will need to build a link from the HTML document you are creating to connect to some other piece of information available on the Internet. For more information, see Curling Up To URLs (v0.2)

How are URLs Structured?

The structure of a URL is:

     type://in.ter.net.address/ directory/sub-directory/... /filename

The "type" indicates the type of Internet server being accessed:

http: A World Wide Web server that provides World Wide Web documents. "HTTP" stands for HyperText Transfer Protocol.
gopher: an Internet Gopher site, menu driven directories of files and information
ftp: An anonymous File Transfer Protocol (FTP) site, archives of files
telnet: Initiates a Telnet session to log on remotely to another computer. When selected, your WWW browser will launch a Telnet external program and connect to the specified site.
WAIS: Wide Area Indexed Server- a site to search a collection of subject oriented documents by keywords
file: A file on your local computer system (hard drive, floppy, local file server)

The type is always followed by "://" and the Internet adress of a remote computer. This is in the structure of:


     host.domain.domain.domain

For example:


     machine.department.college.edu
     123.45.6.78
     company.com
     agency.branch.gov
     machine.organization.country

If the URL is to the main level of this host, then the URL is terminated with a backslash "/". If you are pointing at a sub-directory or a file, you must also add the exact path to that item using the backslash character to indicate the file path.

Experimenting With URLs

Note that the URL can point to any site, directory, subdirectory, text file, image, digital movie, or sound file on any Internet site that is set up for public access. From the list below, look at the URL and then see what happens when you select an anchor tag that uses the URL:

Sample URLs

http: http://www.mcli.dist.maricopa.edu/ MCLI's WWW server; http://www.mcli.dist.maricopa.edu/laby-forum.html Another WWW document from MCLI; http://www.mcli.dist.maricopa.edu/GIFs/read.gif A graphic image from MCLI; http://www.mcli.dist.maricopa.edu/sounds/welcome.au A sound file from MCLI
gopher: gopher://marvel.loc.gov/ Library of Congress Gopher.; gopher://marvel.loc.gov/11/research/locis Sub directory of Library of Congress Gopher; gopher://marvel.loc.gov/00/locis/hours File on Library of Congress Gopher
ftp: ftp://m-media.muohio.edu/ Multimedia Developers FTP site; ftp://m-media.muohio.edu/MultiMedia Sub directory of Multimedia Developers FTP site; ftp://m-media.muohio.edu/MultiMedia/0read1st.txt Text file from Multimedia Developers FTP site; ftp://m-media.muohio.edu/MultiMedia/ShowPict.sea.hqx Download a Macintosh program from Multimedia Developers FTP site; ftp://m-media.muohio.edu/MultiMedia/utilities.dir/RunAPW.ZIP Download a DOS application from Multimedia Developers FTP site

Review Topics

What purpose do URLs serve for the World Wide Web?
Where are URLs found on a WWW screen?
What is the basic structure of an URL?
What are some different servers that can be accessed using URLs?

Independent Practice

Find some sites on the Internet that intrigue you. For each one, record its name and its URL displayed near the top of the WWW browser window. You will use this list later to add anchor links from your own WWW pages to these sites that you found. Or better yet, investigate the Bookmarks or Hotlist features of your Web browser.

Coming Next....

You will use URLs in anchor tags to create links to file Internet for your Volcanoes! page.

| Lesson Index | previous lesson " Links to Local Files" | next lesson "Links to the Internet" |

Writing HTML Lesson 8b: URLs- Pointers to the Internet

The Internet Connection at MCLI is Alan Levine--}
Comments to levine@maricopa.edu