Chapter 1
Understanding the World Wide Web
CONTENTS
One of the best things about the World Wide Web is that it's just
as easy to create Web pages as it is to browse them. The key to
publishing on the Web is having a firm understanding of Hypertext
Markup Language (HTML). Despite the intimidating name, HTML is
extremely simple to learn and use. By the time you finish this
book, you'll be well on your way to becoming an HTML wizard.
Before diving head-first into the language of HTML itself, it
will help you to understand a little bit about how the World Wide
Web works. After all, HTML is designed to guide users through
the vast and tangled resources of the Web. As an HTML author,
you will need to understand some of the basics behind the architecture
of the World Wide Web. Knowing how the Web works, as well as when
it doesn't and why, can help you make important decisions about
how to construct your own Web pages.
It would be impossible to describe in detail the inner workings
of the Web in a single chapter. With that in mind, this chapter
provides you with a "refresher course" on the basics.
Armed with this basic knowledge, you'll be able to move on to
writing your own Web pages in a very short time.
The World Wide Web is a vast collection of information that is
spread across hundreds of thousands of computers around the world.
When you access a document on the Web, there's a lot going on
behind the scenes. Here's a very simple and brief description.
- Many people consider the World Wide Web and the Internet to
be one and the same. The World Wide Web is only part of the Internet,
but it's growing at a faster rate than any other part.
- You can read about how the Internet works in How to Use
the Internet, Third Edition from Ziff-Davis Press.
- The World Wide Web is a network of thousands of computers,
all of which fall neatly into two categories: clients and
servers. Through the use of special software, they form
a kind of network called, not surprisingly, a client-server
network.
- Servers store information and process requests from clients.
Then they send the requested information to the clients. This
information includes all kinds of data, including images, sounds,
and text. Servers also send instructions to the client on how
to display all this information. These instructions are sent in
the form of Hypertext Markup Language (HTML).
- Clients make requests for information and then handle the
chore of displaying that information to the end user. When you
are using a Web browser to navigate the Web, your browsing software
is acting as a client.
- The World Wide Web is a distributed network.
That means there is no central computer for the World Wide Web.
Any server on the Web can be accessed directly by any client.
If a server on the World Wide Web malfunctions, it doesn't affect
the performance of other servers.
- Users navigate the World Wide Web through the use of hypertext
links. When you select or click on a hypertext link, you go to
another area on the Internet. Almost all of the documents on the
Web are interconnected through the use of hypertext links.
- Most of the documents on the World Wide Web are written in
Hypertext Markup Language (HTML). HTML provides instructions for
the client software on how the document should be displayed. HTML
also contains information about how to link up to other documents
on the Web.
Almost every item of information on the World Wide Web can be
accessed directly. That's because every document, file, and image
has a specific address. These addresses are called Uniform
Resource Locators (URLs). URLs are used by Web browsing software
to locate and access information on the World Wide Web. Think
of URLs as postal addresses for the Internet.
- Be very careful when specifying URLs. The Web is very unforgiving
with URLs, and will only accept exact matches. If you receive
a "document not found" message when trying to access
a page on the Web, make sure the URL is typed in correctly.
- Most browsers allow you to store your favorite URLs as "bookmarks."
Use bookmarks to save yourself the trouble of typing in the full
URL each time.
Figure 1.1 :
- The first part of the URL is known as the protocol.
This is almost always http://, which is short for Hypertext
Transfer Protocol. Some URLs start with a different protocol,
such as ftp:// or news://. If you're accessing a
document on your local machine instead of on the Web, the URL
will begin with file://.
Figure 1.2 :
- The second part of the URL is known as the domain name.
If you've used e-mail on the Internet, you're probably already
familiar with domains. The domain represents the name of the server
that you're connecting to.
Figure 1.3 :
- The third part of the URL is called the directory path.
This is the specific area on the server where the item resides.
Directory paths on Web servers work a lot like they do on your
desktop computer. To locate a particular file on a server, you
need to indicate its directory path first.
Figure 1.4 :
- The fourth part of the URL is called the document file
name. This indicates the specific file being accessed.
This is usually an HTML file, but it can also be an image, sound,
or another file.
Figure 1.5 :
- Sometimes the URL contains a fifth part, known as the anchor
name. This is a pointer to a specific part of an HTML document.
It's always preceded by the pound sign (#). Anchors are especially
useful for large documents.
Your Web browser is your gateway to the World Wide Web. A browser
is the client software that allows you to access and view any
document on the Web. There are a number of Web browsers that you
can use to access the Web, and the number of choices available
grows every month.
Even if you're an accomplished Web surfer, it's a good idea to
keep up to date on the most popular browsers. Different Web browsers
have different features, and they all display Web pages with slight
variations. Older Web browsers, which are still in widespread
use, often have trouble displaying some of the newer HTML 3.2
features. If you're planning to create Web pages with HTML, you'll
want to test them with a number of different Web browsers.
In this section, we'll take a look at Netscape, which is the most
popular browser available today.
- Not all browsers look alike. Read the documentation for your
Web browser for specific details.
- New Web browsers are constantly being released, and existing
ones are updated regularly. Make sure you're using the most recent
version of your Web browser. You can usually find updates on the
home page of your Web browser's publisher.
Figure 1.6 :
- To navigate to a Web page, you can type in the URL for the
page here.
- Use these directional buttons to navigate backward and forward
through the list of documents you have recently accessed.
- The button with the house on it always takes you back to your
home page, no matter where you are. By default, most browsers
set this button to display their home page, but you can specify
the URL for your home page in the Options menu.
- Text that is highlighted in a different color usually indicates
that it is hypertext. When you click on this hypertext, your Web
browser follows the link to a another place on the Web. This is
the basic form of navigation on the World Wide Web.
- The status bar keeps you informed about the progress of a
page as your Web browser loads it. Some Web browsers will use
the status bar to let you know the URL of the page you're currently
on, or the URL of the page that a hypertext link points to.
- Experiment with your Web browser to get an understanding of
how navigation works on the World Wide Web. It's a good idea to
use a few different browsers and note the differences. Knowing
how users browse the Web is an important part of understanding
how you should construct your own HTML pages.
Using a hypertext link to move from one place to another is one
of the most common activities on the World Wide Web. In fact,
hypertext links are the very essence of the Web. This lesson explains
how to use a link and describes a little of what happens behind
the scenes.
- Most Web browsers allow you to change the style and appearance
of hypertext links. Look under the Options menu in your browser.
- You can create a link to any object on the Web. Links can
point directly to images or files as well as to different HTML
documents.
Figure 1.7 :
- To find a link on the page, look for text that's displayed
in a different color. By default, hypertext links you haven't
used are blue. Links you've already visited are purple. These
colors can be changed, however.
Figure 1.8 :
- Using your mouse, place the pointer over the hypertext link
and click. There will be a brief delay after you press on the
hypertext link.
- During this delay, your browser client is contacting the Web
server referenced in the hypertext link's URL. It is attempting
to retrieve the referenced document.
Figure 1.9 :
- Once the contact has been established, your browser begins
displaying the new document.
- Not all links appear as text. Many links appear in images,
such as buttons or icons. Sometimes a colored border will appear
around the image, or it will be designed to look like a button.
In many browsers, the cursor will change to a hand when it passes
over a hypertext link. These visual clues help the reader understand
that it is a link. However, sometimes there are no visual clues.
Understanding the need to provide visual clues is an important
part of being an HTML author.
