Transcript Department of Information Technology

Department of Information Technology
Chapter 1: Introduction to the
Internet & the World Wide Web
Prepared by: Ms Melinda Chung
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Objectives
Department of
Information Technology
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Review the history of the Internet.
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Learn what computer networks and internets
are and how they work.
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Learn about the working of the Internet and
WWW.
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Compare different methods for connecting to
the Internet
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Basic definitions
Department of
Information Technology
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A network is a structure linking computers together to
share resources
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Network Interface Card (NIC): a card used to
connect a computer to a network of other computers.
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Users access a network through a computer called a
host or node
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Server - a computer that makes a service available to
a network, runs software that coordinates information
flow among other computers
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Basic definitions
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Information Technology
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Client: computers connected to a server.
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Network Operating System: software that
runs on a server.
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Client/Server Networks: one server
computer sharing its resources with multiple
client computers.
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Local Area Network (LAN): network of
computers located close to each other.
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Client/Server LAN
Department of
Information Technology
New Perspectives on the Internet, 5e
Tutorial 1
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Basic definitions
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Internet
international network of networks - basically
hardware
-uses a standard communication protocol TCP/IP
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World Wide Web
a network providing access to the
information superhighway using graphical
interfaces
 WWW Consortium (W3C)
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Connecting Computers to a
Network – Wireless Networks
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Becoming more common as costs continue to
drop.
Welcome in organizations that occupy old
buildings.
Popular with companies whose employees
use laptop computers.
Used by schools in classrooms, libraries, and
study lounges.
Used in homes.
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Wireless Home Network
Department of
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New Perspectives on the Internet, 5e
Tutorial 1
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Wide Area Networks
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Information Technology
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WAN: a network of networks or an
internet.
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Internet: a worldwide collection of
interconnected networks; owners have
voluntarily agreed to share resources
and network connections.
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Wide Area Networks
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Information Technology
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Wide area network (WAN) - a network
that covers a wide area, such as several
buildings or cities.
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Internet - the largest WAN in existence.
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Connectivity: Circuit Switching
vs Packet Switching
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Circuit switching:
centrally controlled
 single-connection method
 used by most local telephone traffic today
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Vulnerable to destruction of signal
control point or any link in the single path
that carries the signal.
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Connectivity: Circuit Switching
vs Packet Switching
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Information Technology
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Packet-switching: files and messages
broken down into packets and labeled
electronically with codes for their origin and
destination.
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Packets travel from computer to computer
along the network until they reach their
destination.
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Routers determine the best way for a packet
to move towards its destination.
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Connectivity: Circuit Switching
vs Packet Switching
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Information Technology
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Routers use routing algorithms programs to
determine best path for packets.
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Packet-switched networks more reliable:
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rely on multiple routers instead of central point
of control.
each router can send individual packets along
different paths if parts of the network are not
operating.
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Origins of the Internet
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Information Technology
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Early 1960s by the U.S. Department of Defense
(DOD).
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Major research project authorized as a part of
national security.
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Explored ways to connect large mainframe
computers and weapons installations distributed
all over the world.
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Origins of the Internet
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DARPA researchers connected first computer
switches in 1969.
 ARPANET grew over next three years to include
over 20 computers. In its early days, the Internet
was called ARPANET, consisted of two network
nodes located at UCLA and Stanford, connected by
a phone line.
 Computers communicated to other computers on
the network by using Network Control Protocol
(NCP).
 Protocol: collection of rules for formatting, ordering,
and error-checking data sent across a network.
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The Internet today
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Today the Internet has grown to include
hundreds of millions of interconnected
computers, cell phones, PDAs,
televisions, and networks.
 The physical structure of the Internet
uses fiber-optic cables, satellites, phone
lines, and other telecommunications
media.
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Internet and World Wide Web:
Amazing Developments
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Information Technology
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The Internet is a large collection of computers
all over the world connected to one another.
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One of the most amazing technological
developments of the 20th century.
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The World Wide Web is a subset of computers
on the Internet that has helped make Internet
resources available to people who are not
computer experts.
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Internet and World Wide Web:
Amazing Developments
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New Ways to Communicate
E-mail
 Electronic discussions
 Instant messaging
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Information Resources and Software
Newspapers & magazines
 Government documents
 Research reports & books
 Software download sites
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Internet and World Wide Web:
Amazing Developments
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Doing Business Online
Electronic storefronts
 Coordinate worldwide operations
 Recruit employees
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Entertainment
Review restaurants, movies, theater,
musical events and books.
 Interactive games
 Follow sports teams
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Structure of the Internet
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Growth of the Internet
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Connections are cheap & varied …..
 More resources are being connected
 No official control on the Internet
 The WWW protocals made the Internet
more user friendly
 Standards are critical for the success of
new innovations
 Technology advancement & improvement
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Growth of the Internet
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Number of hosts connected to Internet
includes only computers directly connected to
the Internet.
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Internet traffic now carries more files that
contain graphics, sound, and video, so Internet
files have become larger.
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New Structure for the Internet
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The Internet has become one of the most
amazing technological and social
accomplishments of the century.
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Computers linked to this interconnected
network are located in almost every country of
the world.
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Billions of dollars change hands every year
over the Internet.
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Who controls the Internet?
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No one???
 Internet Society - http://www.isoc.org/
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- a non-profit, non-governmental,
international, professional membership
organization
> 150 organization and 16,000 individual
members in over 182 countries
deals with issues that confront the future of
the Internet
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World Wide Web
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World Wide Web: a way of thinking about
information storage and retrieval.
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Web: software that runs on some of the
computers connected to each other through
the Internet.
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Two important innovations played key roles:
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hypertext
graphical user interfaces (GUIs)
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Hypertext and Graphical User
Interfaces Come to the Internet
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Hypertext Markup Language (HTML): a
language that includes a set of codes (or tags)
attached to text.
 Hypertext Server: a computer that stores
files written in HTML; other computers connect
to it and read files.
 Hypertext Link (hyperlink): points to another
location in the same or another HTML
document.
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Hypertext and Graphical User
Interfaces Come to the Internet
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Web Browser: software that lets users read
HTML documents and move from one HTML
document to another through hypertext link tags in
each file.
HTML: a subset of Standard Generalized Markup
Language (SGML).
SGML: has been used by organizations for many
years to manage large document-filing systems.
GUI (graphical user interface): a way of
presenting program output using pictures, icons,
and other graphical elements.
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The Web and Commercialization
of the Internet
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Information Technology
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Businesses quickly recognized profit-making
potential offered by a world-wide network of
easy-to-use computers.
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The Netscape Navigator Web browser was an
instant success.
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Internet Explorer Web browser entered the
market soon after Netscape’s success became
apparent.
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Connection Options
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Information Technology
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NAPs (network access points) offer
connections to large organizations and
businesses.
 Those businesses provide Internet access to
other business and individuals as ISPs.
 Internet service providers (ISPs) provide
customers with software to connect to the ISP,
browse the Web, send and receive e-mail
messages, and perform other Internet-related
functions.
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Hierarchy of Internet Service
Providers
New Perspectives on the Internet, 5e
Tutorial 1
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Connection Bandwidth
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Bandwidth: amount of data that can travel
through a communications circuit in one
second.
 Bandwidth depends on the type of connection
ISP has to the Internet and the kind of
connection you have to the ISP.
 Available bandwidth for any type network
connection between two points is limited to
narrowest bandwidth that exists in any part of
the network.
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Connection Bandwidth
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Bandwidth measured in bits per second (bps).
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When you extend your network beyond a local
area, the speed of the connection depends on
type of connection used.
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POTS (or plain old telephone service) is one
way to connect computers or networks over
longer distances.
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Connection Bandwidth
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Digital Subscriber Line (DSL): higher grade of
service offered by some telephone companies.
Integrated Services Digital Network (ISDN):
first technology developed using a DSL protocol;
offers bandwidths up to 256 Kbps.
Asymmetric Digital Subscriber Line (ADSL):
offers transmission speeds ranging from 16 Kbps
to 9 Mbps.
T1 or T3 connections: often used by
businesses and large organizations; much more
expensive than POTS or ISDN connections.
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Connection Bandwidth
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Internet 2: operated by group of research
universities and the NSF; has backbone
bandwidths greater than 10 Gbps.
Cable connection: increasingly available in the
U.S.; can deliver up to 10 Mbps to an individual
user.
Satellite connection: appealing to users in
remote areas; can download at a bandwidth of
approximately 400 Kbps.
Fixed-point wireless connections: offered by
some companies
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technology similar to wireless LANs
limited and more expensive.
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Connecting Through an
Internet Service Provider
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Reliable connectivity at a reasonable price.
Terms of AUPs usually less restrictive.
Offer modem connections to individuals and
higher speed connections to businesses.
 Quality of service may deteriorate significantly
over time if ISP adds many new customers
without expanding bandwidth.
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Connecting Through Your
Cable Television Company
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Cable modem converts digital signals into radiofrequency analog signals similar to television
transmission signals.
 Signals travel over the same lines that carry cable
television signals.
 Cable connection can provide very fast downloads to
your computer from the Internet (up to 170 times faster
than a telephone line connection).
 Greatest disadvantage for most people is that cable
connection is not available in all areas.
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Connecting by Satellite
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Satellite Internet connections may be only
option available in rural areas.
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Speeds and monthly fees similar to those of
cable and DSL providers.
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Installation fee usually considerably higher
because the dish must be installed and aimed
at the satellite.
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Summary
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Department of
Information Technology
The Internet and the Web began in the military and
research communities.
The Internet and the Web have become an important
worldwide infrastructure.
The Internet and the Web support many resources
through one of the most powerful communication
tools the world has ever known.
There are a number of options for connecting your
computer and the computers of businesses and other
organizations to the Internet.
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Internet & WWW: Amazing
developments
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Information Technology
New ways of communication
Information
resouces &
software
Entertainment
Doing business
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Internet & WWW: Amazing
developments
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Department of
Information Technology
For more information - visit
http://www.zakon.org/robert/internet/ti
meline/
THE END
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