Transcript Internet and World Wide Web: Amazing Developments

Internet and World Wide
Web: Amazing Developments
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Internet- A large collection of computers all
over the world that are connected to one
another in various ways
The Internet can be used to:
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e-mail (electronic mail)- Communicate with
other people throughout the world
access articles (e-zines)- Read magazines,
newspapers, and books online
join discussion groups- Discuss virtually any
topic online
participate in games and simulations
obtain free software (downloads)
World Wide Web
A subset of computers connected to the each
other on the Internet that allow users easily
access other computers in that subset.
Computer Networks
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Computers can be linked together to form an
network by inserting a network interface card
into each computer and connecting them to the
server with a cable.
Network Interface Card (NIC)- A device used
to connect a computer to a network.
Server
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Any computer that accepts requests from other
computers (called clients) that are connected
to it.
The server runs software that allows the
computers to communicate with each
other. This software is called a Network
Operating System.
Server (Cont.)
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This network is called a Client/server network and is
used to connect computers located very close together.
This type of connection is also called a local area
network (LAN) because the direct connection from one
computer to another only works over short distances.
Computers in a network can share printers, files,
software and other equipment.
Different cable types are used to
connect networks.
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Twisted-pair- The oldest type of cable which telephone
companies have used and is the slowest and least
expensive cable (has been improved to be faster than
coaxial cable).
Coaxial cable- Carries signals 20 times faster than
traditional twisted-pair cable and is the cable most
cable television connections use.
Fiber-optic cable- Transmits information using beams
of light through small strands of glass (fastest and most
expensive connection).
Wireless Networks
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Wireless Networks use wireless transmitters
and receivers that plug into NICs. These
networks are especially useful in older
buildings which lack appropriate wiring.
Wide Area Network
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Wide Area Network (WAN)- An interconnected
network of networks (internet). This WAN may
also be connected to the Internet (a collection
of interconnected networks whose owners
have agreed to share resources.
How the Internet Began
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In the 1960's the Department of Defense (DOD) began
examining ways to connect computers around the
world to each other. Advanced Research Projects
Agency (ARPA) was set up to accomplish this task.
Early models for networked computers were the
telephone companies with a single connection between
sender and receiver called Circuit switching
Packet switching
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With Packet switching network files are broken
down into packets that are labeled
electronically with codes for their origin and
destination. The packets travel from computer
to computer along the network until they reach
their destination.
Routers are computers that determine the best
way to move the packet forward to its
destination.
Open architecture philosophy
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Open architecture philosophy- each network
could continue using its own protocols and
data-transmission methods internally.
Protocols
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Vincent Cerf and Robert Kahn developed the
Transmission Control Protocol and the Internet
Protocol (TCP/IP).
In the early 70s Ray Tomlinson wrote a program that
could send and receive messages over the network
and e-mail was born.
TCP/IP protocols included Rile Transfer Protocol (FTP)
and Telnet
History (cont.)
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In the 1980s the ARPANET and other networks
continued to grow and in 1984 ARPANET was
split into ARPANET (would continue its
advanced research activities) and MILNET
(would be reserved for military uses).
As PCs became more powerful and affordable,
firms increasingly used them to construct
LANs. Today we use the term intranet to
describe LANs or WANs that use the TCP/IP
protocol.
Growth of the Internet
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A formal definition of Internet was adopted in
1995:
In 1991, the NSF began implementing plans to
privatize much of the Internet. The estimate of
Internet users is probably underestimated
because:
Popularity of the Internet
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There are over 20 million connected computers
and between 50 and 150 million users on the
Internet today.
Opening the internet to businesses help
motivate its growth. Additional motivations
were Hypertext and Graphical User Interfaces.
World Wide Web
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Hypertext is a method of allowing text in one document
to point to other text in that or another document. Tim
Berners-Lee developed the code for this hypertext
server program and made it available on the Internet.
Most people use a Web Browser (Microsoft Internet
Explorer or Netscape) which is software that lets users
read documents and move from one document to
another.
Browsers Created
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In 1994, Andreessen joined Silicon Graphics to
found Netscape. Microsoft created its Internet
Explorer Web browser soon after.
Connection Options
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Organizations and businesses provide Internet
access to other businesses and
individuals. These firms who provide access
are called Internet Service Providers
(ISPs). ISPs usually provide:
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Software needed to connect to the ISP
Web browsing and e-mail software
Other functions such as file transfer, remote login,
consulting, and web design
Connecting Through Your School or
Employer
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One of the easiest ways to connect to the
Internet is through your school or
employer. Most colleges are connected and
may offer Internet access to their students,
faculty, and other employees.
Connecting Through and Internet
Service Provider
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When you shop for an ISP inquire about the
following:
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Monthly fee and number of hours included
Hourly rate for time over the included time
Is the telephone access number local or long
distance
What Internet services are included
Are user-support services available
Connecting Through Your Cable
Television Company
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Cable television connections have a very high
bandwidth (up to 170 times faster than a
telephone line connection) but may cost more
than twice that of an ISP.
The greatest disadvantage is that cable
connections are not available everywhere.
Connecting Via Satellite
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Connections can now be established via
satellite (downlink only). Satellite connections
are 5 to 10 times faster than telephone
connections. May be the only option for those
in remote areas