Internet History
The Beginning: A "Network of Networks"
The seeds of the Internet were planted in 1969, when the Advanced Research
Projects Agency (ARPA) of the U.S. Department of Defense began connecting
computers at different universities and defense contractors The resulting network was called
ARPANET. The goal of this early project was to create a computer network with multiple
paths—in the form of telephone lines—that could survive a nuclear attack or a natural
disaster such as an earthquake. If one part of the network were destroyed, other parts of the
network would remain functional and data could continue to flow through the surviving lines.
ARPA had a second important reason for creating such a network. That is, it would allow
people in remote locations to share scarce computing resources. By being part of the network,
these users could access faraway systems—such as governmental mainframes or university-
owned supercomputers—and conduct research or communicate with other users. At first,
ARPANET was basically a large network serving only a handful of users, but it expanded
rapidly. Initially, the network included four primary host computers. A host is like a network
server, providing services to other computers that connect to it. ARPANET'S host computers
(like those on today's Internet) provided file transfer and communications services and gave
connected systems access to the network’s high-speed data lines. The system grew quickly
and spread widely as the number of hosts grew The network jumped across the Atlantic to
Europe in 1973, and it never stopped growing. In the mid-1980s, another federal agency, the
National Science Foundation (NSF), joined the project after the Defense Department stopped
funding the network. NSF established five “ supercomputing centers” that were available
to anyone who wanted to use them for academic research purposes.
Today, the Internet connects thousands of networks and hundreds of millions of users around
the world. It is a huge, cooperative community with no central ownership. This lack of
ownership is an important feature of the Internet, bccausc it means that no single person or
group controls the network. Although there are several organizations (such as The Internet
Society and the World Wide Web Consortium) that propose standards for Internet-related
technologies and guidelines for its appropriate use, these organizations almost universally
support the Internet’s openness and lack of centralized control. As a result, the Internet is
open to anyone who can acccss it. If you can use a computer and if the computer is connected
to the Internet, you are free not only to use the resources posted by others, but to create
resources of your own; that is, you can publish documents on the World Wide Web,
exchange email messages, and perform many other tasks. This openness has attracted
millions of users to the Internet. Internet access was available to nearly onehalf billion people
worldwide in 2001. The number of actual users continues to climb dramatically.
Internet services
The Internet acts as a carrier for several different services, each with its own distinct features
and purposes The most commonly used Internet services are
≫ The World Wide Web
≫ Electronic mail
≫ News
≫ File Transfer Protocol
≫ Chat
≫ Instant messaging
≫ Online services
≫ Peer to-peer services
To use any of these services, you need a computer that is connected to the Inter* net in some
way. Most individual users connect their computer’s modem to a telephone line (or use a
high-speed connection such as DSL or a cable modem) and set up an account with an Internet
service provider (ISP), a company that provides local or regional access to the Internet
backbone. Many other users connect to the Internet through a school or business network. To
use a specific service, you also need the right type of software. Some programs enable you to
use multiple Internet services, so you do not necessarily need separate applications for each
service.
WWW
The World Wide Web (also known as the Web or WWW) was created in 1989 at the
European Partidc Physics Laboratory in Geneva, Switzerland, as a method for incorporating
footnotes, figures, and cross-references into online documents. The Web's creators wanted to
create a simple way to access any document that was stored on a network, without having to
search through indexes or directories of files, and without having to manually copy
documents from one computer to another before viewing them. To do this, they established a
way to “ link" documents that were stored in different locations on a single computet; or on
different computers on a network.
If you imagine a collection of billions of documents, all stored in different places, but all
linked together in some manner; you might imagine them creating a “web” of interconnected
information. If you extend that collection of documents and their links to cover the entire
globe, you have a “world-wide web” of information. This concept is where the Web gets its
name. Many people believe that the Web and the Internet are the same thing, but this is not
correct. In fact, they are two different things. The Web is a service (a system for accessing
documents) that is supported by the Internet (a gigantic network).
How the Web Works
Web documents can be linked together because they are created in a format known as
hypertext. Hypertext systems provide an easy way to manage large collections of data, which
can include text files, pictures, sounds movies, and more. In a hypertext system, when you
view a document on your computer's screen, you also can access all the data that might Ik
linked to it. So, if the document is a discussion of honey bees, you might be able to click a
hypertext link and sec a photo of a beehive, or a movie of bees gathering pollen from flowers
To support hypertext documents, the Web uses a special protocol, called the hypertext
transfer protocol, or HTTP. A hypertext document is a specially encoded file that uses
the hypertext markup language, or HTML. This language allows a document's author to
embed hypertext links—also called hyperlinks or just links—in the document. HTTP and
hypertext links are the foundations of the World Wide Web. As you read a hypertext
document—more commonly called a Web page—on scrccn, you can click a word or picture
encoded as a hypertext link and immediately jump to another location within the same
document or to a different Web page. The second page may be located on the same computer
as the original page, or anywhere else on the Internet. Because you do not have to leam
separate commands and addresses to jump to a new location, the World Wide Web organizes
widely scattered resources into a seamless whole. A collection of related Web pages is called
a Web site. Web sites arc housed on Web servers, Internet host computers that often store
thousands of individual pages. Copying a page onto a server is called publishing the page, but
the process also is callcd posting or uploading.
Web browser
A Web browser (or browser) is a software application designed to find hypertext documents
on the Web and then open the documents on the user’s computet. A point-and-click browser
provides a graphical user interface that enables the user to click hyperlinked text and images
to jump to other documents or view other data. Several text-based Web browsers are also
available and are used in nongraphical operating systems, such as certain versions of UNIX.
Mosaic and Web browsers that evolved from it have changed the way people use the Internet.
Today, the most popular graphical Web browsers are Microsoft's Internet Explorer and
Netscape Navigator.
URLs
The hypertext transfer protocol uses Internet addresses in a special format, called
a uniform resource locator, or URL. (The acronym is usually pronounccd by
spelling its letters out, as in “U-R-L-") URLs look like this:
type://address/path
In a URL, type specifies the type of server in which the file is located, address is
the address of the server, and path is the location within the file structure of the
server. The path includes the list of folders where the desired file (the Web page itself
or some other piece of data) is located.
E-Mail
The only Internet service that is more frequently used than the Web is electronic mail.
Electronic mail, or e-mail, is a system for exchanging messages through a computer network.
People most commonly use e-mail to send and receive text messages, but depending on the
software you use, you may be able to exchange audio or video messages with someone else.
E-mail was one of the first uses of the Internet, and quickly became a popular feature because
it lets users exchange messages from anywhere in the world. Further, e-mail is less expensive
than using the telephone because there is no charge for using it, beyond the regular fees you
pay your ISP. E-mail is also a faster way to communicate than postal mail because e-mail
messages typically reach their destination in seconds rather than days. E-mail services arc
very easy to access, and this is another reason for e-mail's popularity. You can manage e-mail
through a typical ISP account and a desktop computer, or use a Web-based e-mail service,
which lets you check your messages wherever you have Web access. Many cellular
telephones and pagers provide e-mail features, too. Some e-mail systems can even interact
with any telephone and actually “ read’’ your messages to you. Another advantage of e-mail
is the ability to attach data files and program files to messages. For example, you can send a
message to a friend and attach a digital photograph or some other file to the message. The
recipient then can open and use the document on his or her computer.
E-mail, however, is not a real-time communications system. This means that once you send a
message to someone, you must wait until he or she reads it and sends you a reply. This delay,
however, doesn’t stop people from exchanging billions of messages each year.
What does HTML Tag ?
An HTML tag is commonly defined as a set of characters constituting a formatted command
for a Web page. At the core of HTML, tags provide the directions or recipes for the visual
content that one sees on the Web.
HTML Tags
1.Heading Tags
Any document starts with a heading. You can use different sizes for your headings. HTML
also has six levels of headings, which use the elements <h1>, <h2>, <h3>, <h4>, <h5>, and
<h6>. While displaying any heading, browser adds one line before and one line after that
heading.
Example
<!DOCTYPE html>
<html>
<head>
<title>Heading Example</title>
</head>
<body>
<h1>This is heading 1</h1>
<h2>This is heading 2</h2>
<h3>This is heading 3</h3>
<h4>This is heading 4</h4>
<h5>This is heading 5</h5>
<h6>This is heading 6</h6>
</body>
</html>
This will produce the following result –
This is heading 1
This is heading 2
This is heading 3
This is heading 4
This is heading 5
This is heading 6
2.Paragraph Tag
The <p> tag offers a way to structure your text into different paragraphs. Each paragraph of
text should go in between an opening <p> and a closing </p> tag as shown below in the
example −
Example
<!DOCTYPE html>
<html>
<head>
<title>Paragraph Example</title>
</head>
<body>
<p>Here is a first paragraph of text.</p>
<p>Here is a second paragraph of text.</p>
<p>Here is a third paragraph of text.</p>
</body>
</html>
This will produce the following result –
Here is a first paragraph of text.
Here is a second paragraph of text.
Here is a third paragraph of text
3.Line Break Tag
Whenever you use the <br /> element, anything following it starts from the next line. This
tag is an example of an empty element, where you do not need opening and closing tags, as
there is nothing to go in between them.
The <br /> tag has a space between the characters br and the forward slash. If you omit this
space, older browsers will have trouble rendering the line break, while if you miss the
forward slash character and just use <br> it is not valid in XHTML.
Example
<!DOCTYPE html>
<html>
<head>
<title>Line Break Example</title>
</head>
<body>
<p>Hello<br />
You delivered your assignment ontime.<br />
Thanks<br />
Mahnaz</p>
</body>
</html>
This will produce the following result –
Hello
You delivered your assignment on time.
Thanks
Mahnaz
4.Centering Content
You can use <center> tag to put any content in the center of the page or any table cell.
Example
<!DOCTYPE html>
<html>
<head>
<title>Centring Content Example</title>
</head>
<body>
<p>This text is not in the center.</p>
<center>
<p>This text is in the center.</p>
</center>
</body>
</html>
This will produce following result –
This text is not in the center.
This text is in the center.
5.Horizontal Lines
Horizontal lines are used to visually break-up sections of a document. The <hr> tag creates a
line from the current position in the document to the right margin and breaks the line
accordingly.
For example, you may want to give a line between two paragraphs as in the given example
below −
Example
Live Demo
<!DOCTYPE html>
<html>
<head>
<title>Horizontal Line Example</title>
</head>
<body>
<p>This is paragraph one and should be on top</p>
<hr />
<p>This is paragraph two and should be at bottom</p>
</body>
</html>
This will produce the following result –
This is paragraph one and should be on top
This is paragraph two and should be at bottom
Again <hr /> tag is an example of the empty element, where you do not need opening and
closing tags, as there is nothing to go in between them.
The <hr /> element has a space between the characters hr and the forward slash. If you omit
this space, older browsers will have trouble rendering the horizontal line, while if you miss
the forward slash character and just use <hr> it is not valid in XHTML
