1. What You Will Learn . . .
How the Internet works
Methods for accessing the Internet
The Internet and World Wide Web The Internet and the World Wide Web
Hypertext
Web browsers and Web servers
1 2
What You Will Learn . . .
Parts of a URL
How to access Web pages
Web subject guides and search engines
Use operators to improve search results
Reliability of information on the Web
Most popular Internet services
3 4
The Internet How the Internet Works
Interoperability is the ability to communicate with a
computer even if it is a different brand or model
The Internet is a global, interconnected computer
network in which every computer connected to it can
exchange data with any other connected computer
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2. Accessing the Internet and Web Accessing the Internet
The Internet can be accessed in the following ways:
Dial-up access with Point-to-Point Protocol (PPP)
Digital Subscriber Line (DSL)
You will need: Cable and satellite access
A computer with an operating system, such as Windows,
ih i h Wi d LAN access
MAC OS, or UNIX, that supports Internet protocols
Communications equipment such as a modem, ISDN adapter, Internet history
or Ethernet card
http://www.zakon.org/robert/internet/timeline/
An Internet service provider (ISP)
Web browser software such as Internet Explorer or Netscape
Navigator
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The Internet and Web: What’s the Difference? The Web Site
A Web site is a collection of
The Internet is the physical connection of millions of related Web documents that
networks are made available to the
public
The Web uses the Internet for its existence
The index page, or home
p g ,
The W b
Th Web consists of h
i t f hypertext embedded on Web
t t b dd d W b
page, is the first page of a
pages that are hosted on Web sites
Web site
Web pages are individual
Web documents
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Web Browsers and Servers
The Hypertext Concept
Hypertext is a way of presenting information so that
the order in which it’s read is left up to the reader
Hyperlinks are underlined or highlighted words that
can be used to view another document or Web page
Web browsers display a Web document and enable
p y
Hypermedia refers to a link to multimedia, such as users to link to other Web pages
music and movies The first browsers were text-only
The Web is a distributed hypermedia system or a Mosaic was the first graphical browser (April 1993)
system where the responsibility for creating content Web servers respond to the requests of browsers.
is distributed among many people They find and send requested resources back to the
browser
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3. Mosaic Web Addresses (URLs)
Web addresses are an addressing system that identifies
where a Web resource is located
The uniform resource locator (URL) is the standard
used to identify Web resources
The URL consists of:
Protocol Server contains Path Resource
identifies the domain identifies the specifies the
the means name of the location of the filename of the
June 1993 Ver.: 0.1a of access Web server document resource
Nov 1993 Ver.: 1.0
Oct 1995 Ver.: 2.0 URL http://www.yahoo.com/ help/shop/ shop-01.html
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The Web Browser’s Window
Browsing the Web Click to view the various parts of a Web browser’s window.
To access a Web page, you can do any of the History Button– List of
Program icon–
Other Navigation Buttons
Animates when
following: Standard Web Button– Prints
Printer
Toolbar–
Back & Forward Buttons– sites visited over a
Favorites Button– List Opens
Media Button–
documents
Address Bar–
downloading
Search Button– player of time
Contains Navigation buttons
RefreshButton– Opens program
Button– visited
Stop Button– Web pages of
Take you to recently period
media Contains URL of
Click a hyperlink Home engine program
bookmarked Returns
Updates downloading
search (refreshes) the
toStops start page E-Mail Button– Opens
pagesdefault
Web page
page
Type a URL in the Address box e-mail program
Click a button on the Links toolbar Hyperlinks
Use the Back and Forward buttons
Use a Web site’s navigation aids Status bar– Messages
about the browser’s
Use the History list operation
Use the Favorites or Bookmarks list
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IP Address Domain Names
Names are easy to remember than IP addresses
Internet Protocol (communications standard) http://hk.yahoo.com = 202.43.220.99
In Windows, “run” → “cmd”→ “nslookup”
A unique id no. (just like your postal address)
You can own your domain names
Typical IP address: 216.27.61.137
For .com, .net, .org, .us…etc.
IP is assigned by network administrator
e.g. www.networksolution.com
You can check your IP (Windows)
“run” → “cmd” → “ipconfig”
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4. Uploading and Downloading Emerging Technologies
Downloading – document or Ways to share information on the Internet
file is transferred from Wiki – open-content encyclopedia
another computer to your Weblog (blog) – Internet journal or diary
computer Moblog (mobile blog) - content posted from a portable
Uploading – files transferred
p g phone or PDA
from your computer to
another computer
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Finding Information on the Web
Using Search Engines
Ways to find information on To use a search engine, you:
the Web:
Choose a search engine (MSN, Lycos, Alta-Vista, Yahoo,
Browse or surf the Web – This etc)
involves linking from one Web
Type in one or more words describing your topic
page to another, and so forth
oa o e ,a d o
Search the Web – This method The search engine checks its database of Web pages
involves using search engines to that contain the words typed
locate Web pages with the The results are sent to your computer
information you’re looking for
Clicking on the link takes you to that page
Subject guides – Web pages are
grouped under headings
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Using Search Techniques Using Search Techniques
The following tables show the results of using and not using
search operators Using Search Operators
Learning a few search techniques can increase the
Words Entered Possible Results – Web
accuracy of Web searches No Search Operators pages containing
Searches using search operators will improve search Words
Entered
Possible Results –
Web pages
+Fire+station Fire station
performance containing +Fire+station*
Fire station
Fire stations
Fire
Most h i h following
M search engines use the f ll i search h station +Fire-station* Fire
Fire station
operators: Fire station “Fire station” Fire station
Inclusion/exclusion operators Fire and station Fire station
Wild cards Fire
Phrases Fire or station station
Fire station
Boolean operators Fire not station Fire
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5. Rules for Evaluating Web Pages Using the Web for Schoolwork
1. Author – Who is the author? Use authoritative online sources
2. Sources – Where does the information come from? Use your library to find articles and books
3. Server – Who provides the server for the page? Cite online and offline references
4. Objectivity – Is the information objective or one-
sided?
5. Style – Is the language objective or argumentative?
6. Purpose – What is the purpose of the page?
7. Accuracy – Is the information accurate?
8. Currency – Is the page up-to-date?
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E-Mail: Staying in Touch E-Mail Addresses
myname@someserver.com
Users name@name of the server that the user is on
E-mail is short for electronic mail
It’s the most popular of the Internet services
Messages are sent and received in a few seconds
Attachments such as photos, music files, and any
document may be sent with the message
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Instant Messaging: E-Mailing Made Faster
Spam: Can It Be Stopped?
Spam – unsolicited e-mail
advertising
With Spam the recipient pays the
postage
To avoid spam
Avoid posting your e-mail
address Instant messaging systems let a user know when a friend or
Use spam protectors business associate is online
Don’t reply to spam It provides a means of communicating through real-time,
text-based conversations
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6. IRC: Text Chatting in Real Time File Transfer Protocol (FTP)
Your Computer FTP Server
DOWNLOAD
UPLOAD
FTP is a part of the Internet that enables client computers to
transfer files
Transferring files from an FTP site to the client is known as
Internet relay chat consists of real-time, text-based downloading
conversations Transferring files from the client to an FTP site is known as
Chat groups are divided into channels that cover a uploading
specific topic Clients may store files on an FTP site’s server
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Usenet Standard Newsgroup Subcategories
Usenet is the part of the comp computer applications, databases, multimedia
Internet which enables users
to participate in discussions misc activism, books, business, health
and newsgroups sci chemistry, archeology, math
Usenet newsgroups are
soc human rights, world cultures
organized into hierarchies
(categories) and subcategories talk Euthanasia, gun control, religion
Subcategories include news Usenet announcements
Standard, Alt, Biz, and Local
rec sports, gardening, bicycles
newsgroups
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Summary
Listservs: Electronic Mail Lists
• The Internet is the network of networks
A listserv is an automatic • The Internet is accessed by way of an ISP
list server • World Wide Web is a global system with
Mail is sent to everyone billions of hypertext document
on the list when e-mail is • Related information is linked using hypertext
g yp
generated. • A Web browser is a program that displays Web
It is similar to a pages
newsgroup or a forum • URL consists of a protocol, a server, a path, and
a resource name
• Search engines enable you to search huge
databases of Web documents
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7. Summary (continued)
• You can improve search results using
operators
• You should always evaluate information
you receive from the Web
• Popular Internet services Wired and Wireless Communication
• E-mail
• Instant messaging
• Internet Relay Chat
• File Transfer Protocol
• Discussion groups
• Listservs
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What You Will Learn . . . What You Will Learn . . .
The definition of bandwidth Multiplexing and digital telephony and their impact
The bandwidth needs of a typical user on line usage
How modems change digital signals into analog Examples of how digitization and convergence are
Transmission media and methods blurring the boundaries between popular
communication devices
i i d i
Limitations of public switched telephone network
(PTSN) for sending and receiving data Various wired and wireless applications
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Connectivity Moving Data: Bandwidth and Modems
Communications – sending and receiving messages
Communications channels – paths through which
messages are passed
Signals can be:
Analog – data is in continuous waveforms
g
the ability to link various media and devices Digital – data is in discontinuous pulses (0’s & 1’s)
digital
analog
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8. Moving Data: Bandwidth and Modems Moving Data: Bandwidth and Modems
Bandwidth – the amount of data that can be Modems
transmitted through a given communications channel Transmit data over telephone lines
Analog measured in cycles per second (Hz) Modulation – converts digital (from computer) to analog to
Digital measured in bits per second (bps) cross telephone lines
Broadband – any transmission medium that transports Demodulation – converts analog (phone lines) to digital for
computer
t
high volumes of data at high speeds
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Wireless Transmission Media Wireless Transmission Media: Twisted Pair
Wireless transmission media refers to the methods
of carrying data through the air or space using Twisted Pair – two
infrared, radio, or microwave signals insulated wires twisted
around each other –
used for telephone
p
wires
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Wireless Transmission Media: Coaxial Cable Wireless Transmission Media: Fiber Optic
Coaxial Cable – center copper wire surrounded by
insulation, surrounding a layer of braded wire Fiber-optic cable – thin strands
of glass that carry data by light
pulses
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9. Wireless Transmission Media: Infrared Wireless Transmission Media: Radio
Radio is a wireless transmission medium that carries
Infrared is a wireless transmission medium that
data via radio frequency signals
carries data via light beams
Wireless LANs in a home or business are one type of radio
Transmitter and receiver must be in line of sight
technology
An IrDa port is needed to use infrared with a computer
Radio signals can be long range (between cities or regions)
and short range (within a building)
Radio signals are susceptible to noise and electrical
interference
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Wireless Transmission Media: Bluetooth Wireless Transmission Media: Microwaves
Short-range radio Microwaves are high-
transmission technology frequency radio waves
Devices identify each other by Much of long-distance
identification number
telephone service is carried by
Connection is confirmed microwaves
i
before it is made final
Microwaves travel in a straight
Does not require a line of sight
line
Microwave relay stations are
built about 30 miles apart
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Wireless Transmission Media: Satellites Wired Communication via the PSTN
The public switched telephone network (PSTN) is
Satellites are microwave relay stations suspended in the world telephone system
space It is used for data as well as voice communications
They are positioned in geosynchronous orbits Twisted-pair wire and fiber-optic cable provide the
connections for the system
Satellites use microwave signals to transmit data to
Home and business phones are connected to subscriber
p
and from earth-based microwave relay stations
df th b d i l t ti loop carriers (SLCs)
The area serviced by SLCs is called the local loop
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10. Multiplexing Last Mile Technologies
The “last mile” refers to the phone lines that connect
homes and businesses to the local loop
Multiplexing technology enables simultaneous multi- The inability of users to access the high-speed fiber-optic
use of transmission lines cable creates a bottleneck of data called the last mile
Copper wire allows up to 24 simultaneous calls per wire problem
Fiber-optic cable permits up to 43,384 calls per strand
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Convergence: Is it a Phone or a
Last Mile Technologies
Computer?
Digital telephony technologies that use twisted-pair
wire are referred to as last mile technologies Digitization – transformation of data into digital
ISDN form
DSL
Convergence – merging of disparate objects or ideas
Cable Modems
into e
i t new combinations
bi ti
Leased lines
SONET
MMDS
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Cellular Telephones Risk of Using Cell Phones????
Cellular telephones enable calls to be
placed through a wireless
telecommunications system
Frequency (Hertz, Hz)
Cellular phones use radio or infrared signals Power (Watt, W)
Cells are limited geographic transmission
areas
A mobile telephone switching office
(MTSO) monitors the signal strength of
cellular phones
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11. Personal Communication Service (PCS) Web-Enabled Devices
Personal Communication Service (PCS) A Web-enabled device is any device that can display
refers to digital cellular telephone service and respond to HTML or XML
technologies
PDAs, cell phones, and tablet PCs are Web-enabled
Digital cellular phones offer: devices
Noise-free
N i f sound d
Improved coverage
Protection from eavesdropping and phone fraud
Voice recognition
High-speed Internet access
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Wired and Wireless Applications Wired and Wireless Applications
Internet telephone – using the Internet for real-time Videoconferencing – using sound and video
voice communications technologies to meet with others
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Facsimile (Fax) Transmission Satellite Radio, GPS
Satellite radio - broadcasts are transmitted through a
satellite
GPS – global positioning systems
27 earth orbiting satellites
g
Navigation systems
Fax transmission is the means of sending an image of
a document over telephone lines
Fax modems support fax as well as data protocols
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12. Text, Picture, and Video Messaging Summary
• Bandwidth is the data transfer capacity of a
Text messaging – sending text communication channel
communications over a cell
phone
• A modem is used to send digital data over a
phone line
Picture messaging – using • Physical and wireless media are used to
y
camera phones to send pictures
h t d i t
to other cell phones
communicate with technology
• The public switched telephone network (PSTN)
is mostly digital
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Summary
• Multiplexing is the transmission of more than
one communication on a single line
• Digitization is the transformation of data into
digital form
• Internet telephony and faxing can be
p y g
accomplished through the Internet
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