Introduction to the Internet by kesavilar


What is the Internet? Introduction about internet...

More Info
									Chapter 1

Introduction to the Internet

1.1 What is the Internet?

1.1.1 Definition
A network is a collection of computers interconnected through some kind of medium so
that they can communicate. This medium can be a copper cable, fiber optic cable, or a
wireless medium such as electromagnetic waves (light, radio waves, etc.). We can
classify these networks depending on their geographical extent; a Local Area Networks
(LAN) spreads over a limited geographical area and in contrast a Wide Area Network
(WAN) connects computers over a much larger geographic area
   An internetwork connects independent LANs and WANs to form one large network.
Such a network is called an internet. There is one such global internet (figure 1.1) that
stemmed from an experimental network started by the Advanced Research Project
Agency of the United States Department of Defense in 1960s. Now this network spans
over political and geographical boundaries. That particular internet is called the Internet.
When we refer to this particular internetwork we always capitalize the first letter “I”.
   The individual networks on the internet are administered and owned by different
persons and organizations and they use different technologies to connect computers. The
Internet uses different technologies to connect these networks together; some networks

       There is no pre-determined distance to differentiate a WAN from a LAN.


are connected to each other over a public telephone networks while others are connected
over satellite links.

   It is a wonder that computers communicate over this widely diverse and most often
incompatible collection of networks. This is possible because of a common set of rules
that they all adhere to despite the differences in the individual LAN or WAN
technologies. Such a set of rules used for communication is called a protocol and the
protocol used in the Internet is called the TCP/IP protocol suite.

   Figure 1.1: Internet is the worldwide, publicly accessible network of interconnected
                                    computer networks

1.1.2 Global infrastructure
The Internet is a giant network spread through out the world by connecting different
types/levels of computers (from personal computers to high end work-stations). Although
these computers are at homes, offices, schools/universities and government departments,
it appears as an Information retrieval system with communication facilities to all users of
the Internet. At the same time, it is a system which is available on demand at all times.

                                                                1.1 What is the Internet?

1.1.3 Communication system
Not like the telephone system which has very limited number of services (voice phone,
fax etc.), the Internet has unlimited number of services. At the same time, these services
can be offered simultaneously (multi tasking environment) based on the users demand.
Applications which run (execute) at computers connected to the Internet can provide
these services.
       1. Email
       2. Instant messaging
       3. Discussion forums (forums on website, news groups etc.)

1.1.4 Information retrieval system
Information can be sent from any computer to any other if it is connected through a
network. There are various types of resources available for information retrieval.
   One major resource is web sites or home pages of organizations or individuals like Another resource that can be used for information retrieval is search
engines. is a very popular search engine. You can also find books and
reports and repositories of software applications and so much more.

1.1.5 Who pays for it?
Who pays for the Internet? Do you have to pay for the Internet Access?
   There are no owners for the Internet. Then you do not want to pay for it. However,
these networks should be developed and maintained by the providers. Therefore those
who provide network connectivity (we call them Internet Service Providers) have to
charge individuals/organizations when they want to access the Internet through their
   Generally, there are two types of fees: One for the access time and the other one for
the internet connectivity. Access time is usually based on the local telephone charges
(e.g. Dial up Connection) or a fixed amount irrespective of access time (e.g. ADSL
Connection In some countries, Internet connection can be obtained through Cable TV
networks. In some countries, Internet connection can be obtained through Cable TV


networks. At the same time, an individual or organization can obtain a dedicated direct
connection to the Internet (e.g. Leased line provided by SLT) if they want to have very
high speed connection and the charges for such connections are usually high.

1.1.6 The Impact of the Internet
The Internet is creating a big impact on the society by revolutionizing the way people live
and work in the everyday life. There is a huge impact in several key areas like the
Government sector, Commerce or Business sector, and also in Education sector.
   The impact continues beyond what mentioned above. Entertainment is an-other area
which has started to make a direct impact on the life. On the other hand, the cost of some
of services could bring to zero once they are provided through the Internet. For example,
consider, voice calling to a long distance location through the Internet.
   The Internet globalizes communication by allowing users from around the world to
connect with each other. Ultimately, we hope that the Internet would bring people,
services and different cultures together into a small village. eGovernment

Many government services have been made available through the Internet and this
initiative is known as eGovernment (figure 1.2). eGovernment is a tool for governments
to use new technologies to provide people with more convenient access to government
information and services to improve quality of services and provide opportunities to
participate in democratic institutions and processes.
   eGovernment provides opportunities to move forward in the 21st century with high
quality, cost effective government services delivery and the creation of better
relationships between the people and the government.

                                                                  1.1 What is the Internet?

   Figure 1.2: People do not want to spend many hours to obtain government services eCommerce / eBusiness

People do not have to visit physical stores/super markets to buy products. They can query
about products through online stores and can order them immediately by paying through
Electronic Fund Transferring Cards (Eg: Visa, Master, Diners Club Etc.). This buying
and selling process is described as e-commerce (figure 1.3). In fact, the process of buying
and selling goes more than two party interaction when customers pay through credit cards
(your bill will be settled probably through a bank) and get those goods through a delivery
service like DHL, Fedex or normal postal service. This whole business process can be
powered through Internet by providing an interface through the Word Wide Web
(described later). This revolution is termed as the e-Business.
   To many people the term ”electronic commerce” means shopping on the part of the
internet called World Wide Web (The web). However, it also includes many other
activities such as business trading with other businesses and internal processes that
companies use to support their buying, selling, hiring, planning etc. In many cases the
term eBusiness is used in this broader sense.


              Figure 1.3: You don’t have to visit supermarkets to buy goods eLearning

Going beyond the government services and business transactions, the Internet is
penetrating into the education sector and it will be creating the biggest impact in the
society. E-Learning is the framework which integrates the power of Information
Communication Technology to provide learning solutions through the Internet (figure
1.4). E-Learning probably minimizes much discrimination in society due to education
privileges, especially in rural communities.

1.2 History of the Internet

1.2.1 Early years of the Internet
In the early years of the Internet, by the late 1970s, many independent LAN networks
were emerged due to two reasons. First is due to the introduction of the inexpensive
minicomputers. Second reason is introduction of the inexpensive easy to install LAN
technologies. LAN technologies (figure 1.5) solve the problem of computer
communication in a way that is inexpensive and reliable. LAN technology changed the
way people worked by enabling resource sharing. Before LAN technologies,

                                                               1.2 History of the Internet

   Figure 1.4: By linking universities, colleges, schools and homes into a world wide
               network, the Internet is creating a big impact in the society

each computer had specific input/output devices like printers and one copy of the data or
software. But with the introduction of the LAN technology a set of computers could share
resources like printers. As there were many different LAN technologies companies
installed the LAN technology that best met their needs. Most large organizations had
several LAN technologies in use in different departments
   Suppose an organization has two LANs one in the accounting department and one in
the Human Resource (HR) division. If one needs to transfer information that is stored on
a computer in the HR division to a computer in the accounting department connecting the
two cables may not make it possible if the two LANs are using different technologies. So
there was a problem in sharing information between different LANs.

1.2.2 Emergence of WANs
It is not always possible to connect multiple LANs together as different LAN
technologies can be incompatible.


         Figure 1.5: A Local Area Network spreads over a limited geographical area

   In 1960s and 1970s scientists came out with WANs that connected multiple
computers across large geographical distances. So with this a company with offices in
several cities can install a WAN that links computers in each city. All attached computers
can communicate with each other. However WANs cost much more than LANs. Hence
LANs were much popular than WANs. Engineers invented many WAN technologies
most of them were incompatible with one another. A Single Network

Still there were many problems in accessing resources. For example, say in an
organization if one computer attaches to a LAN and another attaches to a WAN, neither
has access to all resources in the organization. The goal was to have a usable single
network where each computer in an organization has access to all resources, with some
restrictions on the resources a given computer or user can access.

                                                              1.2 History of the Internet

  Figure 1.6: A Wide Area Network connects computers over a much larger geographic

By the late 1970s, the U.S. department of Defense through Advanced Research Project
Agency (ARPA) (figure 1.7) had several computer networks to pass technology on to the
military. Its goal was to support military research about how to build a network that could
continue to function in the midst of partial outages that could be caused by bomb attacks.
It included a WAN called ARPANET. ARPA also had the same problem in sharing
resources. ARPA research examined how to interconnect all machines to form a large
single network. ARPANET Backbone

ARPANET also called as the backbone network, allowed smaller local networks to
connect to it. Once these smaller networks were connected to the backbone, they were in
effect connected to each other. In 1969 the Internet, then known as the ARPANET, was
brought online under a contract let by the ARPA which initially connected four major
computers at universities in the southwestern US. They are UCLA, Stanford Research
Institute, UCSB, and the University of Utah.


                              Figure 1.7: The ARPA network

Useful URLs


1.2.4 Internet Standards: TCP/IP
Internet standards forms an important part of the technology that makes it possible to
interconnect networks. Two pieces of the Internet standards are, The Internet Protocol
(IP) software which Provides basic communication, Transmission Control Protocol
(TCP) software which provides additional facilities that applications need.
       Most of the time, the entire set of Internet Communication Software is identified
as TCP/IP by the initials of the two components with a slash in between. More formal
name is The TCP/IP Internet Protocol Suite and it’s more accurate as it points out that,
the entire set contains more than just the two protocols.

                                                               1.2 History of the Internet Protocol

When two persons want to communicate with each other, they must know the same
language. Just like that, computers on the Internet must know the same language or adapt
to a set of standard rules to communicate with one another and the term, protocol, is used
to refer the standard rules of communication. Hence, the standards or rules of
communication on the Internet (i.e. The Internet Protocol) are known as TCP/IP.

1.2.5 Open system
ARPA made the research results public to encourage vendors to adopt Internet
technology. Whenever a researcher discovered some thing important took measures to
document the results in a report. ARPA made all reports available to public.
   Researchers who devised the Internet published technical information also in a series
of reports that describe the Internet and the TCP/IP it uses. As the project documentation
was accessible across the network the researchers could coordinate their activities easily.

1.2.6 Military uses TCP/IP
By 1982, a prototype Internet was used and the TCP/IP technology had been tested.
   Some of the academic and industrial research sites were using TCP/IP regularly. U. S.
military also started to use TCP/IP and chose the internet as its primary computer
communication system. By 1983, ARPA expanded the Inter-net to include all military
sites connected to the ARPANET. The date, Marked a transition for the Internet as it
changed the Internet from an experiment to a useful network.


1.2.7 Doubles In Size In a Year
Before 1982, the Internet interconnected approximately 200 computers. One year later, it
had doubled in size. Increase in Internet size uncovered limits in TCP/IP. As more and
more computers connected to the Internet the TCP/IP couldn’t accommodate all. There
was a need to update TCP/IP to increase the capacity and also required tuning of
administrative procedures by professional staff. The National Science Foundation funded
a project (CSNET) to build the Computer Science Network. CSNET encouraged
institutions to use TCP/IP to connect to the Internet.

1.2.8 Adaptability
Many services face difficulties when the demand increases and if they cannot support all
their customers. When service provider increases its capacity, it may ask their customers
to acquire new equipments and their old equipments become obsolete. This issue is
known as backward compatibility.
   However, this is not an issue in the Internet, although new equipments are integrated
to the system. Simply we can say, continual expansion of the Internet is possible by
adapting to both technical and political changes.
   What we can observe is that, the Internet continues to expand (figure 1.8).

1.2.9 NSF’s Approach
The Internet changed the way scientists do research. They could exchange documents or
experimental data instantly and also used the Internet to disseminate data as experiments
proceed. So the scientists could analyze the results of experiments done at a remote place
without travelling and also used the Internet for informal, unpublished discussions.
   Recognizing the importance of the Internet to the science, NSF decided to fund
Internet growth and TCP/IP technology. In 1986, the National Science Foundation
funded NSFNET as a cross country 56 Kbps backbone for the Inter-net. This network
was much smaller and not much faster than the ARPANET. Later NSF decided to extend
network access to every scientist.

                                                               1.2 History of the Internet

                          Figure 1.8: Internet is growing rapidly

   They maintained their sponsorship for nearly a decade, setting rules for its non-
commercial government and research uses. And because the NSF Network was so
successful, ARPANET was dissolved in 1990 and many of the sites connected to it were
absorbed by the NSFNET.

1.2.10 Exponential Growth
Internet has grown rapidly during the recent past. This is mainly due to the fact that the
services and opportunities available through the Internet are growing very fast.
   According to the recent statistics, a computer is added to the Internet in every second.
It is expected the number of computers connected to the Internet will be doubled every 10
months and the growth has an exponential trend now. Accommodating the access growth

In order to accommodate this access growth of the Internet, it is necessary to develop
technological capabilities and infrastructure of the Internet. Many inter national
organizations and governments are contributing to improve the Internet.


1.2.11 The Future of the Internet
The incubator for many of the emerging technologies shaping the future is known as
Internet2. Internet2

Formed in 1996 and administered by the University Corporation for Advanced Internet
Development (UCAID), Internet2 is a partnership between universities, corporations and
government agencies.
   Internet2 is not a single network, but a consortium of hundreds of high-speed
networks linked by fiber optic backbones that span the United States and links to other
   The network transmits data at speeds up to 2.4 gigabits per second–45,000 times
faster than a 56 Kbps modem– allowing scientists to test their laboratory discoveries in
the real world.

1.3 Why do people use the Internet?

1.3.1 Who is using the Internet?
Everyday the numbers of users are increasing. Current statistics say that the largest
portion is from US and Europe. However, Asian users are rising rapidly.
   The Internet has become a resource irrespective of profession or status. At the same
time, their usage objective varies and some individuals may have different objectives. For
example, children, parents, teachers and researchers may access the Internet mainly for
education purposes and stockbrokers and different business professionals for business
   Anyone can connect to the Internet through telephone lines since these two networks
are connected. You need a device called a modem to connect your computer to Internet
through a telephone line.

                                                         1.3 Why do people use the Internet? Why would YOU want to use it?

Besides, individuals, business, trade, commerce and industry, the Internet also provides
tremendous opportunities to students, researchers and professionals for getting
information on matters related to academic and professional topics. In addition to that the
Internet is a source of information. It is a good source of entertainment too. We will look
into the facilities provided by the Internet in brief.

1.3.2 Internet Facilities
The Internet makes it possible to communicate and share information in a number of
ways. Two of the most popular uses of the Internet are electronic mail and the World
Wide Web. We can also find several other useful services like Instant messaging, video
conferencing, FTP, newsgroups, etc.

1.3.3 WWW
WWW stands for the World Wide Web which is sometimes called as w3 or Web is the
most popular and powerful application on the Internet. It was originally created to build
the infrastructure for sharing documents on the Internet.
   Since different types of computers will access these documents, it was decided to
have a standard structure for them. This standard was called HTML (HyperText Markup
   Today the web is a huge collection of documents stored on computers around the
world. HTML

HTML was derived based on another document language called SGML(Standard
Generalized Markup Language). Hence web documents usually have html mark up
commands to format these documents. It was called web since html gives facilities to link
documents with respect to specific locations. These locations are identified using file
addressing mechanism called URL (Uniform Resource Locator).


URL identifies a file using its physically stored location, file name and if necessary
segment name in the file.

1.3.4 Email
If you are a user of the Internet, you can get an address called the email address. Then
others can send you messages to your email address and you can read them when ever
you want. This is like when you give the postal address of your home, others can send
mail to your address. Postal Mail takes time and more costly than emails. Emails are
instant and the cost of delivery is very small.
   Do you have an email address? If not, do you like to get one? How much will it cost?
It is just few keystrokes and you can get one for free too. We will learn more about
emails later.

1.3.5 Chat
Chatting is a method of communication and is a very popular activity that people engage
through the Internet. When two or more people are online (i.e. they are connected to the
Internet at the same time), they can exchange messages as a private group or in an open
chat room where anyone else can participate with or without their permission. Email
based communication is considered as the asynchronous method of communication
where participants do not want to be online. Whereas, chatting is considered to be
synchronous method of communication and it opens a direct interactive environment.
   Earlier, chatting was done using simple text messages since it didn’t take much time
for the transmission. With the development of the Internet speed and band-width, people
can now do chatting using audio and video streams just like in a real-time
communication. Irrespective of the medium of chatting, it is almost free except the
charges to access the Internet.

1.3.6 Video conferencing
It is usually a bi-directional communication between two or more parties using video
streams and special hardware in a real time communication. Since video

                                                      1.3 Why do people use the Internet?

stream requires better (bandwidth) and faster (speed) connection, it is not a very popular
way of communication on the Internet in early days.
   Video conferencing is more than mere communication and it may involve more
collaborative activities. Video conferencing tools provide additional facilities for active
collaboration, for example white boards.
   Examples for video conferencing include MSN messenger for video conferencing or
Microsoft Netmeeting Special Hardware

Video conferencing is now becoming a common mechanism due to the better
technological infrastructure of the Internet. You need a video camera, microphone
attached to a computer to start video conferencing with another party on the Internet.

1.3.7 Newsgroups
When you want to send a message to one or very few individuals you can send it by
email. However, if you want to start a discussion based on these messages, emailing is
not the best option. Newsgroups serve this purpose and it provides an interface for such
discussions. Simply, you can send a message to a newsgroup and then all people who are
in this group can see your posting and reply to it. Such replies also appear in this
   It also can be considered as an electronic bulletin board. Usenet is one such famous
newsgroup but there are several others. Most of the time, these groups are based on some
specific interest which is identified by the topic given to the group.

1.3.8 FTP
FTP which stands for File Transfer Protocol is a standard way to copy files from one
location to another (i.e. from one machine location to another location in the same or
different machine). You can use FTP to download files to your machine from a location
in another machine.


   However, you need to login into these machines in order to obtain the per-mission.
There are some public locations on the Internet from which you can download files by
just giving your identification information if you like.
   In order to simplify the process of accessing files through FTP, there are several
applications just like web browsers. Then, users do not need to know complicated
commands and they can copy files or directories just like copying files on the desktop.
   We will be exploring these Internet services in detail in upcoming chapters.


To top